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Findings

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.

Published Apr 30, 2026 · updated Jun 17, 2026 · exim exim

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.

Code

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No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 30, 2026 · NIST NVD

    Detected

    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.

  2. Jun 17, 2026 · NIST NVD

    Updated

    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.

Affected

  • cpe exim/eximversion unspecified

Sources

  • CVE.orgVulnerability recordCVE-2026-40684

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-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.

    nvd.nist.gov

References