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TI-2026-81160 Aliases CVE-2026-117556GHSA-xcf7-q4j8-4wvv

Heap out-of-bounds read in zchunk header parsing

Priority LOW 30CWE-125Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Passive
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
None · None · Low
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat.

Summary

zchunk before 1.5.5 contains a heap out-of-bounds read in read_preface() in src/lib/header.c, which passes the total header length instead of the remaining bytes to compressed integer parsing functions (CWE-125). A remote attacker can supply a crafted .zck file whose header ends inside a compressed integer, causing reads past the heap header buffer and crashing the application.

Written with Claude Haiku 5.5 from the sources below · 2026-11-03

Description from the CNA

zchunk before 1.5.5 contains a heap out-of-bounds read vulnerability in read_preface() in src/lib/header.c that passes the total header length instead of remaining bytes to compint parsing functions. Attackers can supply a crafted .zck file whose header ends inside a compressed integer, causing reads past the heap header buffer and crashing the application.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00328 26th percentileScored 2026-11-07
Fix Fixed zchunk (zchunk): 1.5.5Red Hat: 1 advisory

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
zchunkzchunkbefore 1.5.51.5.5Patch availableCNA
  • zchunk Vendorzchunk Affected before 1.5.5 Fixed in 1.5.5 Patch available CNA

Remediation

Update zchunk to version 1.5.5 or later. Red Hat fixes this in Red Hat Hardened Images through RHSA-2026:90996.

Written with Claude Haiku 5.5 from the sources below · 2026-11-03

  • Fix · CNA zchunk (zchunk) Fixed in 1.5.5

Red Hat 1 advisory

  • RHSA-2026:90996 Released 2026-10-27 · Red Hat rating Low
    Red Hat Hardened Images RPMs bug fix and enhancement update
    • Red Hat Hardened Images zchunk-1.5.5-1.hum1@aarch64, zchunk-1.5.5-1.hum1@s390x, zchunk-1.5.5-1.hum1@src +7

Vendor assessments

Red Hat

Red Hat rating: Low. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Hardened ImagesFixed RHSA-2026:90996

Timeline

  1. 2026-10-27 Threatist record created from CVE-2026-117556
  2. 2026-10-27 Alias added: GHSA-xcf7-q4j8-4wvv
  3. 2026-10-28 CISA SSVC decision points changed
  4. 2026-11-02 Affected versions changed · Red Hat
  5. 2026-11-02 CVSS score added · Red Hat
  6. 2026-11-03 Fix available: RHSA-2026:90996 · Red Hat
  7. 2026-11-03 Fix available: Red Hat Hardened Images · Red Hat

References

Patch 1

Other 4

  • TI-2023-24855 zchunk before 1.3.2 has multiple integer overflows via malformed zchunk files to… CVSS 3.1HIGH 7.8

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences