November 14, 2026

CVE Watchtower

CVE-2026-1257427-Zip Out-of-bounds Write

NVD

Vulnerability Summary

7-Zip before 26.06 contains a heap out-of-bounds write vulnerability in the LZX decoder that lets attackers corrupt memory when a continuation CAB volume declares a smaller window. Attackers can entice victims to extract crafted multi-volume CAB archives, where a stale _pos value bypasses bounds checks, enabling arbitrary code execution.
Severity Level
HIGH(8.5)
Published Date
Nov 10, 2026
Last Modified
Nov 12, 2026
Exploitation Status
Public exploit available
EPSS Score (30-Day)
0.18%Probability
Root Weakness (CWE)
CWE-787: Out-of-bounds Write ↗
The product writes data past the end, or before the beginning, of the intended buffer.
CVSS v4.0 Base Metrics — Score 8.5 (HIGH)
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Attack VectorLocal
Attack ComplexityLow
Attack RequirementsNone
Privileges RequiredNone
User InteractionPassive
Confidentiality (Vulnerable System)High
Integrity (Vulnerable System)High
Availability (Vulnerable System)High
Confidentiality (Subsequent System)None
Integrity (Subsequent System)None
Availability (Subsequent System)None
Show CVSS v3.x metrics (score 7.8)
CVSS v3.1 Base Metrics — Score 7.8 (HIGH)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack VectorLocal
Attack ComplexityLow
Privileges RequiredNone
User InteractionRequired
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

Affected & Patched Versions

Affected Versions
  • 7-Zip 7-Zip < 26.06
Patched Versions
  • 7-Zip 7-Zip 26.06

What to do

Prioritize this fix. Exploit code is public, so attacks can follow quickly.

  1. Check whether you run 7-Zip and which version.
  2. Update to a patched version listed above, then confirm the new version.
  3. Review logs and exposed services for signs of earlier compromise.

Timeline

  • Nov 10, 2026Published
  • Nov 12, 2026Record last modified

Score, severity and exploitation changes are tracked from the day Watchtower started logging them.

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External References

Data last checked: Nov 14, 2026 01:09 UTC