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Fencer Intel
critical 9.8

CVE-2026-115946 json

XS::libbrotli versions before 1.2.1.0 for Perl bundle a brotli library with an out-of-bounds write in the decoder

published 9d ago modified 9h ago also EUVD-2026-114737

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits
0
none known

Summary

XS::libbrotli versions before 1.2.1.0 for Perl bundle a brotli library with an out-of-bounds write in the decoder.

Affected versions compile a bundled brotli into static archives that dependent XS modules link against at build time, rather than using the system library. The bundled copy, 1.0.7 or 1.1.0 across the range, carries the decoder out-of-bounds write described in CVE-2026-111497. Version 1.2.1.0 updates it to brotli 1.2.1.

XS::libbrotli has no Perl interface, so the decoder is reached through any dependent module that decompresses untrusted data with it. An attacker supplying a crafted brotli stream can corrupt decoder state, disclose memory, crash the process, or potentially execute arbitrary code. Upgrading the system brotli does not remediate this.

Patch / fix

  • cpan XS-libbrotli 1.2.1.0

Is CVE-2026-115946 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
3d ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • cpan XS-libbrotli

Classification

Weakness
  • CWE-1395 Dependency on Vulnerable Third-Party Component

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.