Vulnerability-Lookup

CVE-2026-27795 (GCVE-0-2026-27795)

Vulnerability from cvelistv5 – Published: 2026-02-25 17:30 – Updated: 2026-02-25 18:42

Title

LangChain Community: redirect chaining can lead to SSRF bypass via RecursiveUrlLoader

Summary

LangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). Users should upgrade to `@langchain/community` 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. In this version, automatic redirects are disabled (`redirect: "manual"`), each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request, and a maximum redirect limit prevents infinite loops.

Severity ?

4.1 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N

CWE

CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

GitHub_M

References

URL

Tags

	https://github.com/langchain-ai/langchainjs/secur…	x_refsource_CONFIRM
	https://github.com/langchain-ai/langchainjs/secur…	x_refsource_MISC
	https://github.com/langchain-ai/langchainjs/pull/9990	x_refsource_MISC
	https://github.com/langchain-ai/langchainjs/commi…	x_refsource_MISC
	https://github.com/langchain-ai/langchainjs/commi…	x_refsource_MISC
	https://github.com/langchain-ai/langchainjs/relea…	x_refsource_MISC
	https://github.com/langchain-ai/langchainjs/relea…	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	langchain-ai	langchainjs	Affected: < 1.1.18

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-27795",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-02-25T18:42:34.609541Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-02-25T18:42:52.277Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "langchainjs",
          "vendor": "langchain-ai",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.1.18"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "LangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). Users should upgrade to `@langchain/community` 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. In this version, automatic redirects are disabled (`redirect: \"manual\"`), each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request, and a maximum redirect limit prevents infinite loops."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 4.1,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-918",
              "description": "CWE-918: Server-Side Request Forgery (SSRF)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-25T17:30:01.106Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-mphv-75cg-56wg",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-mphv-75cg-56wg"
        },
        {
          "name": "https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7"
        },
        {
          "name": "https://github.com/langchain-ai/langchainjs/pull/9990",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/langchain-ai/langchainjs/pull/9990"
        },
        {
          "name": "https://github.com/langchain-ai/langchainjs/commit/2812d2b2b9fd9343c4850e2ab906b8cf440975ee",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/langchain-ai/langchainjs/commit/2812d2b2b9fd9343c4850e2ab906b8cf440975ee"
        },
        {
          "name": "https://github.com/langchain-ai/langchainjs/commit/d5e3db0d01ab321ec70a875805b2f74aefdadf9d",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/langchain-ai/langchainjs/commit/d5e3db0d01ab321ec70a875805b2f74aefdadf9d"
        },
        {
          "name": "https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.14",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.14"
        },
        {
          "name": "https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.18",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.18"
        }
      ],
      "source": {
        "advisory": "GHSA-mphv-75cg-56wg",
        "discovery": "UNKNOWN"
      },
      "title": "LangChain Community: redirect chaining can lead to SSRF bypass via RecursiveUrlLoader"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-27795",
    "datePublished": "2026-02-25T17:30:01.106Z",
    "dateReserved": "2026-02-24T02:31:33.265Z",
    "dateUpdated": "2026-02-25T18:42:52.277Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-27795",
      "date": "2026-04-18",
      "epss": "0.00042",
      "percentile": "0.12519"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-27795\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-02-25T18:23:41.153\",\"lastModified\":\"2026-04-13T14:15:35.920\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"LangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). Users should upgrade to `@langchain/community` 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. In this version, automatic redirects are disabled (`redirect: \\\"manual\\\"`), each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request, and a maximum redirect limit prevents infinite loops.\"},{\"lang\":\"es\",\"value\":\"LangChain es un framework para construir aplicaciones impulsadas por LLM. Antes de la versi\u00f3n 1.1.8, existe una omisi\u00f3n de falsificaci\u00f3n de petici\u00f3n del lado del servidor (SSRF) basada en redirecci\u00f3n en `RecursiveUrlLoader` en `@langchain/community`. El cargador valida la URL inicial, pero permite que la recuperaci\u00f3n subyacente siga las redirecciones autom\u00e1ticamente, lo que permite una transici\u00f3n de una URL p\u00fablica segura a un endpoint interno o de metadatos sin revalidaci\u00f3n. Esto es una omisi\u00f3n de las protecciones de SSRF introducidas en 1.1.14 (CVE-2026-26019). Los usuarios deben actualizar a `@langchain/community` 1.1.18, que valida cada salto de redirecci\u00f3n deshabilitando las redirecciones autom\u00e1ticas y revalidando los objetivos de `Location` antes de seguirlos. En esta versi\u00f3n, las redirecciones autom\u00e1ticas est\u00e1n deshabilitadas (`redirect: \u0027manual\u0027`), cada `Location` 3xx se resuelve y valida con `validateSafeUrl()` antes de la siguiente petici\u00f3n, y un l\u00edmite m\u00e1ximo de redirecciones evita bucles infinitos.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N\",\"baseScore\":4.1,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"REQUIRED\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"LOW\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":2.3,\"impactScore\":1.4},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N\",\"baseScore\":7.4,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"REQUIRED\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":2.8,\"impactScore\":4.0}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-918\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:langchain:langchain_community:*:*:*:*:*:node.js:*:*\",\"versionEndExcluding\":\"1.1.18\",\"matchCriteriaId\":\"82E0218B-5EC7-4779-9F3F-FF40F63DEA54\"}]}]}],\"references\":[{\"url\":\"https://github.com/langchain-ai/langchainjs/commit/2812d2b2b9fd9343c4850e2ab906b8cf440975ee\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Patch\"]},{\"url\":\"https://github.com/langchain-ai/langchainjs/commit/d5e3db0d01ab321ec70a875805b2f74aefdadf9d\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Patch\"]},{\"url\":\"https://github.com/langchain-ai/langchainjs/pull/9990\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Issue Tracking\"]},{\"url\":\"https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.14\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Release Notes\"]},{\"url\":\"https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.18\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Release Notes\"]},{\"url\":\"https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Not Applicable\"]},{\"url\":\"https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-mphv-75cg-56wg\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Vendor Advisory\"]}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-27795\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-02-25T18:42:34.609541Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-02-25T18:42:46.808Z\"}}], \"cna\": {\"title\": \"LangChain Community: redirect chaining can lead to SSRF bypass via RecursiveUrlLoader\", \"source\": {\"advisory\": \"GHSA-mphv-75cg-56wg\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"CHANGED\", \"version\": \"3.1\", \"baseScore\": 4.1, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"REQUIRED\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"NONE\", \"privilegesRequired\": \"LOW\", \"confidentialityImpact\": \"LOW\"}}], \"affected\": [{\"vendor\": \"langchain-ai\", \"product\": \"langchainjs\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 1.1.18\"}]}], \"references\": [{\"url\": \"https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-mphv-75cg-56wg\", \"name\": \"https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-mphv-75cg-56wg\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7\", \"name\": \"https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/langchain-ai/langchainjs/pull/9990\", \"name\": \"https://github.com/langchain-ai/langchainjs/pull/9990\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/langchain-ai/langchainjs/commit/2812d2b2b9fd9343c4850e2ab906b8cf440975ee\", \"name\": \"https://github.com/langchain-ai/langchainjs/commit/2812d2b2b9fd9343c4850e2ab906b8cf440975ee\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/langchain-ai/langchainjs/commit/d5e3db0d01ab321ec70a875805b2f74aefdadf9d\", \"name\": \"https://github.com/langchain-ai/langchainjs/commit/d5e3db0d01ab321ec70a875805b2f74aefdadf9d\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.14\", \"name\": \"https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.14\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.18\", \"name\": \"https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.18\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"LangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). Users should upgrade to `@langchain/community` 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. In this version, automatic redirects are disabled (`redirect: \\\"manual\\\"`), each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request, and a maximum redirect limit prevents infinite loops.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-918\", \"description\": \"CWE-918: Server-Side Request Forgery (SSRF)\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-02-25T17:30:01.106Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-27795\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-02-25T18:42:52.277Z\", \"dateReserved\": \"2026-02-24T02:31:33.265Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-02-25T17:30:01.106Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

GHSA-MPHV-75CG-56WG

Vulnerability from github – Published: 2026-02-25 22:59 – Updated: 2026-02-25 22:59

Summary

LangChain Community: redirect chaining can lead to SSRF bypass via RecursiveUrlLoader

Details

Summary

A redirect-based Server-Side Request Forgery (SSRF) bypass exists in RecursiveUrlLoader in @langchain/community. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019).

Affected Component

Package: @langchain/community
Component: RecursiveUrlLoader
Configuration: preventOutside (default: true) is insufficient to prevent this bypass when redirects are followed automatically.

Description

RecursiveUrlLoader is a web crawler that recursively follows links from a starting URL. The existing SSRF mitigation validates the initial URL before fetching, but it does not re-validate when the request follows redirects. Because fetch follows redirects by default, an attacker can supply a public URL that passes validation and then redirects to a private network address, localhost, or cloud metadata endpoint.

This constitutes a “check‑then‑act” gap in the request lifecycle: the safety check occurs before the redirect chain is resolved, and the final destination is never validated.

Impact

If an attacker can influence content on a page being crawled (e.g., user‑generated content, untrusted external pages), they can cause the crawler to: - Fetch cloud instance metadata (AWS, GCP, Azure), potentially exposing credentials or tokens - Access internal services on private networks (10.x, 172.16.x, 192.168.x) - Connect to localhost services - Exfiltrate response data through attacker-controlled redirect chains

This is exploitable in any environment where RecursiveUrlLoader runs with access to internal networks or metadata services, which includes most cloud-hosted deployments.

Attack Scenario

The crawler is pointed at a public URL that passes initial SSRF validation.
That URL responds with a 3xx redirect to an internal target.
The fetch follows the redirect automatically without revalidation.
The crawler accesses the internal or metadata endpoint.

Example redirector:

https://302.r3dir.me/--to/?url=http://169.254.169.254/latest/meta-data/

Root Cause

SSRF validation (validateSafeUrl) is only performed on the initial URL.
Redirects are followed automatically by fetch (redirect: "follow" default), so the request can change destinations without additional validation.

Resolution

Upgrade to @langchain/community >= 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating Location targets before following them. - Automatic redirects are disabled (redirect: "manual"). - Each 3xx Location is resolved and validated with validateSafeUrl() before the next request. - A maximum redirect limit prevents infinite loops.

Reources

Original SSRF fix (CVE-2026-26019): enforced origin comparison and added initial URL validation
https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7

Severity ?

4.1 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.1.17"
      },
      "package": {
        "ecosystem": "npm",
        "name": "@langchain/community"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.1.18"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27795"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-25T22:59:48Z",
    "nvd_published_at": "2026-02-25T18:23:41Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\nA redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019).\n\n## Affected Component\n- Package: `@langchain/community`\n- Component: `RecursiveUrlLoader`\n- Configuration: `preventOutside` (default: `true`) is insufficient to prevent this bypass when redirects are followed automatically.\n\n## Description\n`RecursiveUrlLoader` is a web crawler that recursively follows links from a starting URL. The existing SSRF mitigation validates the initial URL before fetching, but it does not re-validate when the request follows redirects. Because fetch follows redirects by default, an attacker can supply a public URL that passes validation and then redirects to a private network address, localhost, or cloud metadata endpoint.\n\nThis constitutes a \u201ccheck\u2011then\u2011act\u201d gap in the request lifecycle: the safety check occurs before the redirect chain is resolved, and the final destination is never validated.\n\n## Impact\nIf an attacker can influence content on a page being crawled (e.g., user\u2011generated content, untrusted external pages), they can cause the crawler to:\n- Fetch cloud instance metadata (AWS, GCP, Azure), potentially exposing credentials or tokens\n- Access internal services on private networks (`10.x`, `172.16.x`, `192.168.x`)\n- Connect to localhost services\n- Exfiltrate response data through attacker-controlled redirect chains\n\nThis is exploitable in any environment where `RecursiveUrlLoader` runs with access to internal networks or metadata services, which includes most cloud-hosted deployments.\n\n## Attack Scenario\n1. The crawler is pointed at a public URL that passes initial SSRF validation.\n2. That URL responds with a 3xx redirect to an internal target.\n3. The fetch follows the redirect automatically without revalidation.\n4. The crawler accesses the internal or metadata endpoint.\n\nExample redirector:\n```\nhttps://302.r3dir.me/--to/?url=http://169.254.169.254/latest/meta-data/\n```\n\n## Root Cause\n- SSRF validation (`validateSafeUrl`) is only performed on the initial URL.\n- Redirects are followed automatically by fetch (`redirect: \"follow\"` default), so the request can change destinations without additional validation.\n\n## Resolution\nUpgrade to `@langchain/community` **\u003e= 1.1.18**, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them.\n- Automatic redirects are disabled (`redirect: \"manual\"`).\n- Each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request.\n- A maximum redirect limit prevents infinite loops.\n\n## Reources\n- Original SSRF fix (CVE-2026-26019): enforced origin comparison and added initial URL validation\n- https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7",
  "id": "GHSA-mphv-75cg-56wg",
  "modified": "2026-02-25T22:59:48Z",
  "published": "2026-02-25T22:59:48Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7"
    },
    {
      "type": "WEB",
      "url": "https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-mphv-75cg-56wg"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27795"
    },
    {
      "type": "WEB",
      "url": "https://github.com/langchain-ai/langchainjs/pull/9990"
    },
    {
      "type": "WEB",
      "url": "https://github.com/langchain-ai/langchainjs/commit/2812d2b2b9fd9343c4850e2ab906b8cf440975ee"
    },
    {
      "type": "WEB",
      "url": "https://github.com/langchain-ai/langchainjs/commit/d5e3db0d01ab321ec70a875805b2f74aefdadf9d"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/langchain-ai/langchainjs"
    },
    {
      "type": "WEB",
      "url": "https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.14"
    },
    {
      "type": "WEB",
      "url": "https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.18"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "LangChain Community: redirect chaining can lead to SSRF bypass via RecursiveUrlLoader"
}

FKIE_CVE-2026-27795

Vulnerability from fkie_nvd - Published: 2026-02-25 18:23 - Updated: 2026-04-13 14:15

Severity ?

4.1 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N
7.4 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N

Summary

References

URL	Tags
security-advisories@github.com	https://github.com/langchain-ai/langchainjs/commit/2812d2b2b9fd9343c4850e2ab906b8cf440975ee	Patch
security-advisories@github.com	https://github.com/langchain-ai/langchainjs/commit/d5e3db0d01ab321ec70a875805b2f74aefdadf9d	Patch
security-advisories@github.com	https://github.com/langchain-ai/langchainjs/pull/9990	Issue Tracking
security-advisories@github.com	https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.14	Release Notes
security-advisories@github.com	https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.18	Release Notes
security-advisories@github.com	https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7	Not Applicable
security-advisories@github.com	https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-mphv-75cg-56wg	Vendor Advisory

Impacted products

	Vendor	Product	Version
	langchain	langchain_community	*

JSON

To clipboard

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:langchain:langchain_community:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "82E0218B-5EC7-4779-9F3F-FF40F63DEA54",
              "versionEndExcluding": "1.1.18",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "LangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in `RecursiveUrlLoader` in `@langchain/community`. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). Users should upgrade to `@langchain/community` 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating `Location` targets before following them. In this version, automatic redirects are disabled (`redirect: \"manual\"`), each 3xx `Location` is resolved and validated with `validateSafeUrl()` before the next request, and a maximum redirect limit prevents infinite loops."
    },
    {
      "lang": "es",
      "value": "LangChain es un framework para construir aplicaciones impulsadas por LLM. Antes de la versi\u00f3n 1.1.8, existe una omisi\u00f3n de falsificaci\u00f3n de petici\u00f3n del lado del servidor (SSRF) basada en redirecci\u00f3n en `RecursiveUrlLoader` en `@langchain/community`. El cargador valida la URL inicial, pero permite que la recuperaci\u00f3n subyacente siga las redirecciones autom\u00e1ticamente, lo que permite una transici\u00f3n de una URL p\u00fablica segura a un endpoint interno o de metadatos sin revalidaci\u00f3n. Esto es una omisi\u00f3n de las protecciones de SSRF introducidas en 1.1.14 (CVE-2026-26019). Los usuarios deben actualizar a `@langchain/community` 1.1.18, que valida cada salto de redirecci\u00f3n deshabilitando las redirecciones autom\u00e1ticas y revalidando los objetivos de `Location` antes de seguirlos. En esta versi\u00f3n, las redirecciones autom\u00e1ticas est\u00e1n deshabilitadas (`redirect: \u0027manual\u0027`), cada `Location` 3xx se resuelve y valida con `validateSafeUrl()` antes de la siguiente petici\u00f3n, y un l\u00edmite m\u00e1ximo de redirecciones evita bucles infinitos."
    }
  ],
  "id": "CVE-2026-27795",
  "lastModified": "2026-04-13T14:15:35.920",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.1,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.3,
        "impactScore": 1.4,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 7.4,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 4.0,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2026-02-25T18:23:41.153",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/langchain-ai/langchainjs/commit/2812d2b2b9fd9343c4850e2ab906b8cf440975ee"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/langchain-ai/langchainjs/commit/d5e3db0d01ab321ec70a875805b2f74aefdadf9d"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Issue Tracking"
      ],
      "url": "https://github.com/langchain-ai/langchainjs/pull/9990"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Release Notes"
      ],
      "url": "https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.14"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Release Notes"
      ],
      "url": "https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.18"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Not Applicable"
      ],
      "url": "https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-mphv-75cg-56wg"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-918"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-27795 (GCVE-0-2026-27795)

GHSA-MPHV-75CG-56WG

Summary

Affected Component

Description

Impact

Attack Scenario

Root Cause

Resolution

Reources

FKIE_CVE-2026-27795

Tags

Sightings

Nomenclature