Vulnerability-Lookup

GHSA-Q496-Q274-JGH9

Vulnerability from github – Published: 2026-05-01 00:31 – Updated: 2026-05-01 18:31

Details

In Exim before 4.99.2, on systems using musl libc (not glibc), an attacker can crash the connection instance when malformed DNS data is present in PTR records. This is caused by a dn_expand oddity in octal printing.

Severity ?

5.9 (Medium)


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

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JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-40684"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-684"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-04-30T22:16:25Z",
    "severity": "MODERATE"
  },
  "details": "In Exim before 4.99.2, on systems using musl libc (not glibc), an attacker can crash the connection instance when malformed DNS data is present in PTR records. This is caused by a dn_expand oddity in octal printing.",
  "id": "GHSA-q496-q274-jgh9",
  "modified": "2026-05-01T18:31:23Z",
  "published": "2026-05-01T00:31:27Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40684"
    },
    {
      "type": "WEB",
      "url": "https://code.exim.org/exim/exim/commit/628bbaca7672748d941a12e7cd5f0122a4e18c81"
    },
    {
      "type": "WEB",
      "url": "https://exim.org/static/doc/security/CVE-2025-40684.txt"
    },
    {
      "type": "WEB",
      "url": "https://exim.org/static/doc/security/CVE-2026-40684.txt"
    },
    {
      "type": "WEB",
      "url": "https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40684.assessment"
    },
    {
      "type": "WEB",
      "url": "https://www.openwall.com/lists/oss-security/2026/04/30/21"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/05/01/11"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-40684 (GCVE-0-2026-40684)

Vulnerability from cvelistv5 – Published: 2026-04-30 00:00 – Updated: 2026-05-01 17:22

Summary

Severity ?

5.9 (Medium)


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

CWE

CWE-684 - Incorrect Provision of Specified Functionality

Assigner

mitre

References

4 references

URL	Tags
https://www.openwall.com/lists/oss-security/2026/…
https://exim.org/static/doc/security/cve-2026-04.…
https://code.exim.org/exim/exim/commit/628bbaca76…
https://exim.org/static/doc/security/CVE-2026-40684.txt

Impacted products

1 product

Vendor	Product	Version
Exim	Exim	Affected: 0 , < 4.99.2 (semver)

Show details on NVD website

JSON

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                  },
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                  },
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                  }
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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.

Action not permitted

GHSA-Q496-Q274-JGH9

CVE-2026-40684 (GCVE-0-2026-40684)

Tags

Sightings

Nomenclature