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CVE-2026-40684

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.
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:07997af017f557d096720c8150ed01d60ec19a07596fff0392e9c5031e13c947
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0

Affected products and versions

1 source assertion
{"defaultStatus":"unaffected","product":"Exim","vendor":"Exim","versions":[{"lessThan":"4.99.2","status":"affected","version":"0","versionType":"semver"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:6de7be0b326ace197d55ae1cb66666394570b7b4c029d492c9431bc257dd2f4e · sha256:bbb0263e0d45ba71… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":5.9,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:6de7be0b326ace197d55ae1cb66666394570b7b4c029d492c9431bc257dd2f4e · sha256:bbb0263e0d45ba71… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

1 source assertion
{"cweId":"CWE-684","description":"CWE-684 Incorrect Provision of Specified Functionality","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:6de7be0b326ace197d55ae1cb66666394570b7b4c029d492c9431bc257dd2f4e · sha256:bbb0263e0d45ba71… · /containers/cna/problemTypes/0/descriptions/0

Source references

5 source assertions
{"url":"http://www.openwall.com/lists/oss-security/2026/05/01/11"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:6de7be0b326ace197d55ae1cb66666394570b7b4c029d492c9431bc257dd2f4e · sha256:bbb0263e0d45ba71… · /containers/adp/1/references/0
{"url":"https://code.exim.org/exim/exim/commit/628bbaca7672748d941a12e7cd5f0122a4e18c81"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:6de7be0b326ace197d55ae1cb66666394570b7b4c029d492c9431bc257dd2f4e · sha256:bbb0263e0d45ba71… · /containers/cna/references/2
{"url":"https://exim.org/static/doc/security/CVE-2026-40684.txt"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:6de7be0b326ace197d55ae1cb66666394570b7b4c029d492c9431bc257dd2f4e · sha256:bbb0263e0d45ba71… · /containers/cna/references/3
{"url":"https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40684.assessment"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:6de7be0b326ace197d55ae1cb66666394570b7b4c029d492c9431bc257dd2f4e · sha256:bbb0263e0d45ba71… · /containers/cna/references/1
{"url":"https://www.openwall.com/lists/oss-security/2026/04/30/21"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:6de7be0b326ace197d55ae1cb66666394570b7b4c029d492c9431bc257dd2f4e · sha256:bbb0263e0d45ba71… · /containers/cna/references/0

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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