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CVE-2026-40686

In Exim before 4.99.2, when utf8 operators are enabled, there is an out-of-bounds read if large UTF-8 trailing characters are present (malformed UTF-8 header data). Information might be divulged within an error message produced during handling of an unrelated e-mail message.
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:10ba9a06054d415b8e8c436b5fa015d444c5b74ee6a02ebd1c4f0e8d02c1a7b6
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:v2:546ba59d6a083ae3e761f5e8c24eb1f666b15cac0c30ef55d98aac3c2b3c3537 · sha256:0e4eb6f41a112728… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":3.7,"baseSeverity":"LOW","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N","version":"3.1"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:546ba59d6a083ae3e761f5e8c24eb1f666b15cac0c30ef55d98aac3c2b3c3537 · sha256:0e4eb6f41a112728… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

1 source assertion
{"cweId":"CWE-125","description":"CWE-125 Out-of-bounds Read","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:546ba59d6a083ae3e761f5e8c24eb1f666b15cac0c30ef55d98aac3c2b3c3537 · sha256:0e4eb6f41a112728… · /containers/cna/problemTypes/0/descriptions/0

Source references

4 source assertions
{"url":"https://code.exim.org/exim/exim/commit/f2570bde16fb4d4a1242ff363a4c4eecf6372efc"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:546ba59d6a083ae3e761f5e8c24eb1f666b15cac0c30ef55d98aac3c2b3c3537 · sha256:0e4eb6f41a112728… · /containers/cna/references/2
{"url":"https://exim.org/static/doc/security/CVE-2026-40686.txt"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:546ba59d6a083ae3e761f5e8c24eb1f666b15cac0c30ef55d98aac3c2b3c3537 · sha256:0e4eb6f41a112728… · /containers/cna/references/3
{"url":"https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40686.assessment"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:546ba59d6a083ae3e761f5e8c24eb1f666b15cac0c30ef55d98aac3c2b3c3537 · sha256:0e4eb6f41a112728… · /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:v2:546ba59d6a083ae3e761f5e8c24eb1f666b15cac0c30ef55d98aac3c2b3c3537 · sha256:0e4eb6f41a112728… · /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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