CVE-2026-27889 (GCVE-0-2026-27889)

Vulnerability from cvelistv5 – Published: 2026-03-25 19:36 – Updated: 2026-06-30 12:08
VLAI
Title
NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead
Summary
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.2.0 and prior to versions 2.11.14 and 2.12.5, a missing sanity check on a WebSockets frame could trigger a server panic in the nats-server. This happens before authentication, and so is exposed to anyone who can connect to the websockets port. Versions 2.11.14 and 2.12.5 contains a fix. A workaround is available. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-points. If one is able to do so, a defense in depth of restricting either of these will mitigate the attack.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: poc Automatable: yes Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-190 - Integer Overflow or Wraparound
  • CWE-1286 - Improper Validation of Syntactic Correctness of Input
Assigner
References
Impacted products
Vendor Product Version
nats-io nats-server Affected: >= 2.2.0, < 2.11.14
Affected: >= 2.12.0, < 2.12.5
Create a notification for this product.
Red Hat Multicluster Global Hub 1.4.5     cpe:/a:redhat:multicluster_globalhub:1.4::el9
 Create a notification for this product.
Red Hat Multicluster Global Hub 1.5.4     cpe:/a:redhat:multicluster_globalhub:1.5::el9
 Create a notification for this product.
Red Hat Multicluster Global Hub 1.6.2     cpe:/a:redhat:multicluster_globalhub:1.6::el9
 Create a notification for this product.
Red Hat Red Hat OpenShift Container Platform 4     cpe:/a:redhat:openshift:4
 Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-27889",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-25T20:06:22.827675Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-25T20:06:31.897Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "affected": [
          {
            "cpes": [
              "cpe:/a:redhat:multicluster_globalhub:1.4::el9"
            ],
            "defaultStatus": "affected",
            "product": "Multicluster Global Hub 1.4.5",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:multicluster_globalhub:1.5::el9"
            ],
            "defaultStatus": "affected",
            "product": "Multicluster Global Hub 1.5.4",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:multicluster_globalhub:1.6::el9"
            ],
            "defaultStatus": "affected",
            "product": "Multicluster Global Hub 1.6.2",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:openshift:4"
            ],
            "defaultStatus": "unaffected",
            "product": "Red Hat OpenShift Container Platform 4",
            "vendor": "Red Hat"
          }
        ],
        "datePublic": "2026-03-25T19:36:36.370Z",
        "descriptions": [
          {
            "lang": "en",
            "value": "A flaw was found in NATS-Server, a high-performance messaging system. A remote attacker can exploit this vulnerability before authentication by sending a specially crafted WebSockets frame. This missing sanity check can trigger a server panic, leading to a Denial of Service (DoS) for affected deployments that use WebSockets and expose the network port to untrusted endpoints."
          }
        ],
        "metrics": [
          {
            "other": {
              "content": {
                "namespace": "https://access.redhat.com/security/updates/classification/",
                "value": "Important"
              },
              "type": "Red Hat severity rating"
            }
          },
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "HIGH",
              "baseScore": 7.5,
              "baseSeverity": "HIGH",
              "confidentialityImpact": "NONE",
              "integrityImpact": "NONE",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
              "version": "3.1"
            },
            "format": "CVSS"
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-1286",
                "description": "Improper Validation of Syntactic Correctness of Input",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-30T12:08:03.315Z",
          "orgId": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
          "shortName": "redhat-SADP"
        },
        "references": [
          {
            "tags": [
              "vdb-entry",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/security/cve/CVE-2026-27889"
          },
          {
            "name": "RHBZ#2451447",
            "tags": [
              "issue-tracking",
              "x_refsource_REDHAT"
            ],
            "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2451447"
          },
          {
            "tags": [
              "x_sadp-csaf-vex"
            ],
            "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27889.json"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:22347"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:21769"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:23345"
          }
        ],
        "solutions": [
          {
            "lang": "en",
            "value": "RHSA-2026:22347: Multicluster Global Hub 1.4.5"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:21769: Multicluster Global Hub 1.5.4"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:23345: Multicluster Global Hub 1.6.2"
          }
        ],
        "timeline": [
          {
            "lang": "en",
            "time": "2026-03-25T20:01:58.261Z",
            "value": "Reported to Red Hat."
          },
          {
            "lang": "en",
            "time": "2026-03-25T19:36:36.370Z",
            "value": "Made public."
          }
        ],
        "title": "github.com/nats-io/nats-server: NATS-Server: Denial of Service via malformed WebSockets frame",
        "workarounds": [
          {
            "lang": "en",
            "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability."
          }
        ],
        "x_adpType": "supplier",
        "x_generator": {
          "engine": "sadp-cli 1.0.0"
        }
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "nats-server",
          "vendor": "nats-io",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 2.2.0, \u003c 2.11.14"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.12.0, \u003c 2.12.5"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.2.0 and prior to versions 2.11.14 and 2.12.5, a missing sanity check on a WebSockets frame could trigger a server panic in the nats-server.  This happens before authentication, and so is exposed to anyone who can connect to the websockets port. Versions 2.11.14 and 2.12.5 contains a fix. A workaround is available. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-points. If one is able to do so, a defense in depth of restricting either of these will mitigate the attack."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-190",
              "description": "CWE-190: Integer Overflow or Wraparound",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-25T19:36:36.370Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/nats-io/nats-server/security/advisories/GHSA-pq2q-rcw4-3hr6",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/nats-io/nats-server/security/advisories/GHSA-pq2q-rcw4-3hr6"
        },
        {
          "name": "https://advisories.nats.io/CVE/secnote-2026-03.txt",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://advisories.nats.io/CVE/secnote-2026-03.txt"
        }
      ],
      "source": {
        "advisory": "GHSA-pq2q-rcw4-3hr6",
        "discovery": "UNKNOWN"
      },
      "title": "NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-27889",
    "datePublished": "2026-03-25T19:36:36.370Z",
    "dateReserved": "2026-02-24T15:19:29.716Z",
    "dateUpdated": "2026-06-30T12:08:03.315Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-27889",
      "date": "2026-07-05",
      "epss": "0.00582",
      "percentile": "0.43606"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-27889\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-03-25T20:16:27.210\",\"lastModified\":\"2026-06-30T03:17:59.350\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.2.0 and prior to versions 2.11.14 and 2.12.5, a missing sanity check on a WebSockets frame could trigger a server panic in the nats-server.  This happens before authentication, and so is exposed to anyone who can connect to the websockets port. Versions 2.11.14 and 2.12.5 contains a fix. A workaround is available. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-points. If one is able to do so, a defense in depth of restricting either of these will mitigate the attack.\"},{\"lang\":\"es\",\"value\":\"NATS-Server es un servidor de alto rendimiento para NATS.io, un sistema de mensajer\u00eda nativo de la nube y del borde. A partir de la versi\u00f3n 2.2.0 y antes de las versiones 2.11.14 y 2.12.5, una comprobaci\u00f3n de cordura faltante en un marco de WebSockets podr\u00eda desencadenar un p\u00e1nico del servidor en el nats-server. Esto ocurre antes de la autenticaci\u00f3n, y por lo tanto est\u00e1 expuesto a cualquiera que pueda conectarse al puerto de websockets. Las versiones 2.11.14 y 2.12.5 contienen una correcci\u00f3n. Una soluci\u00f3n alternativa est\u00e1 disponible. La vulnerabilidad solo afecta a las implementaciones que usan WebSockets y que exponen el puerto de red a puntos finales no confiables. Si uno es capaz de hacerlo, una defensa en profundidad de restringir cualquiera de estos mitigar\u00e1 el ataque.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"nats-io\",\"product\":\"nats-server\",\"versions\":[{\"version\":\"\u003e= 2.2.0, \u003c 2.11.14\",\"status\":\"affected\"},{\"version\":\"\u003e= 2.12.0, \u003c 2.12.5\",\"status\":\"affected\"}]}]},{\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\",\"affectedData\":[{\"vendor\":\"Red Hat\",\"product\":\"Multicluster Global Hub 1.4.5\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:multicluster_globalhub:1.4::el9\"]},{\"vendor\":\"Red Hat\",\"product\":\"Multicluster Global Hub 1.5.4\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:multicluster_globalhub:1.5::el9\"]},{\"vendor\":\"Red Hat\",\"product\":\"Multicluster Global Hub 1.6.2\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:multicluster_globalhub:1.6::el9\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat OpenShift Container Platform 4\",\"defaultStatus\":\"unaffected\",\"cpes\":[\"cpe:/a:redhat:openshift:4\"]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6},{\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-03-25T20:06:22.827675Z\",\"id\":\"CVE-2026-27889\",\"options\":[{\"exploitation\":\"poc\"},{\"automatable\":\"yes\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-190\"}]},{\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-1286\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"2.2.0\",\"versionEndExcluding\":\"2.11.14\",\"matchCriteriaId\":\"6681EAC6-5A1D-4F3A-926C-F7BEB21791AA\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"2.12.0\",\"versionEndExcluding\":\"2.12.5\",\"matchCriteriaId\":\"B141DA72-3502-4746-A246-EE1087C993F4\"}]}]}],\"references\":[{\"url\":\"https://advisories.nats.io/CVE/secnote-2026-03.txt\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Mitigation\",\"Vendor Advisory\"]},{\"url\":\"https://github.com/nats-io/nats-server/security/advisories/GHSA-pq2q-rcw4-3hr6\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Mitigation\",\"Vendor Advisory\"]},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:21769\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:22347\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:23345\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/security/cve/CVE-2026-27889\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://bugzilla.redhat.com/show_bug.cgi?id=2451447\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27889.json\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-27889\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-03-25T20:06:22.827675Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-03-25T20:06:28.024Z\"}}], \"cna\": {\"title\": \"NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead\", \"source\": {\"advisory\": \"GHSA-pq2q-rcw4-3hr6\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7.5, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"nats-io\", \"product\": \"nats-server\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003e= 2.2.0, \u003c 2.11.14\"}, {\"status\": \"affected\", \"version\": \"\u003e= 2.12.0, \u003c 2.12.5\"}]}], \"references\": [{\"url\": \"https://github.com/nats-io/nats-server/security/advisories/GHSA-pq2q-rcw4-3hr6\", \"name\": \"https://github.com/nats-io/nats-server/security/advisories/GHSA-pq2q-rcw4-3hr6\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://advisories.nats.io/CVE/secnote-2026-03.txt\", \"name\": \"https://advisories.nats.io/CVE/secnote-2026-03.txt\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.2.0 and prior to versions 2.11.14 and 2.12.5, a missing sanity check on a WebSockets frame could trigger a server panic in the nats-server.  This happens before authentication, and so is exposed to anyone who can connect to the websockets port. Versions 2.11.14 and 2.12.5 contains a fix. A workaround is available. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-points. If one is able to do so, a defense in depth of restricting either of these will mitigate the attack.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-190\", \"description\": \"CWE-190: Integer Overflow or Wraparound\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-03-25T19:36:36.370Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-27889\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-03-25T20:06:31.897Z\", \"dateReserved\": \"2026-02-24T15:19:29.716Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-03-25T19:36:36.370Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

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.