Vulnerability-Lookup

GHSA-R3C6-FJ5W-6F75

Vulnerability from github – Published: 2026-08-20 21:31 – Updated: 2026-08-20 21:31

Details

tor before 0.4.9.9 was prone to a NULL write after free when sending a CONFLUX_SWITCH cell fails. The return value of relay_send_command_from_edge() was ignored, so a send failure (which calls circuit_mark_for_close() and removes the leg via cfx_del_leg()) would go undetected, causing the caller to write to the now-freed current leg and resulting in a crash. This is TROVE-2026-017.

Severity

6.5 (Medium)


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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-77641"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-252"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-20T21:17:11Z",
    "severity": "MODERATE"
  },
  "details": "tor before 0.4.9.9 was prone to a\u00a0NULL write after free when sending a CONFLUX_SWITCH cell fails. The return value of relay_send_command_from_edge() was   ignored, so a send failure (which calls circuit_mark_for_close()  and removes the leg via cfx_del_leg()) would go undetected, causing the caller to write to the now-freed current leg and resulting in a crash. This is TROVE-2026-017.",
  "id": "GHSA-r3c6-fj5w-6f75",
  "modified": "2026-08-20T21:31:30Z",
  "published": "2026-08-20T21:31:30Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-77641"
    },
    {
      "type": "WEB",
      "url": "https://gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-77641 (GCVE-0-2026-77641)

Vulnerability from cvelistv5 – Published: 2026-08-20 21:09 – Updated: 2026-08-27 16:06

Summary

Severity

6.5 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-27 15:47 UTC

CWE

CWE-252 - Unchecked Return Value

Assigner

mitre mitre root

References

1 reference

URL	Tags
https://gitlab.torproject.org/tpo/core/tor/-/raw/…

Impacted products

1 product

Vendor	Product	Version
torproject	Tor	Affected: 0.4.8.1-alpha , < 0.4.9.9 (custom) cpe:2.3:a:torproject:tor::::::::

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-77641",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-27T15:47:55.296047Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-27T16:06:56.149Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Tor",
          "vendor": "torproject",
          "versions": [
            {
              "lessThan": "0.4.9.9",
              "status": "affected",
              "version": "0.4.8.1-alpha",
              "versionType": "custom"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:torproject:tor:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "0.4.9.9",
                  "versionStartIncluding": "0.4.8.1-alpha",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "tor before 0.4.9.9 was prone to a\u00a0NULL write after free when sending a CONFLUX_SWITCH cell fails. The return value of relay_send_command_from_edge() was   ignored, so a send failure (which calls circuit_mark_for_close()  and removes the leg via cfx_del_leg()) would go undetected, causing the caller to write to the now-freed current leg and resulting in a crash. This is TROVE-2026-017."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-252",
              "description": "CWE-252 Unchecked Return Value",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-20T21:09:41.229Z",
        "orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
        "shortName": "mitre"
      },
      "references": [
        {
          "url": "https://gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog"
        }
      ],
      "x_generator": {
        "engine": "CVE-Request-form 0.0.1"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
    "assignerShortName": "mitre",
    "cveId": "CVE-2026-77641",
    "datePublished": "2026-08-20T21:09:41.229Z",
    "dateReserved": "2026-08-20T21:09:40.882Z",
    "dateUpdated": "2026-08-27T16:06:56.149Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

GHSA-R3C6-FJ5W-6F75

CVE-2026-77641 (GCVE-0-2026-77641)

Tags

Sightings

Nomenclature