zip: legacy Shrink/Reduce/Implode decoder: denial of service from attacker-controlled ZIP64 uncompressed size

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-115907: 0.35% estimated exploitation activity in the next 30 days; percentile 28.73 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A malicious 149-byte ZIP archive can cause a denial of service in applications that enable `legacy-zip` and use `ZipArchive::extract()`. An attacker-controlled ZIP64 uncompressed size triggers a `capacity overflow` panic in the Shrink decoder in optimized builds, potentially terminating the affected process.

Details When reading a Shrink-compressed entry, `ShrinkDecoder::read()` buffers the compressed input and reserves output capacity using the entry's declared uncompressed size: ```rust if !self.stream_read { self.stream_read = true; let mut compressed_bytes = Vec::new(); self.compressed_reader.read_to_end(&mut compressed_bytes)?; self.stream.reserve(self.uncompressed_size as usize); hwunshrink( &compressed_bytes, self.uncompressed_size as usize, &mut self.stream, )?; } ``` In version 8.6.0, this is located in `src/legacy/shrink.rs`. The vulnerable legacy…

Published by the source

29 Oct 2026, 16:40 UTC

Last modified by the source

29 Oct 2026, 17:00 UTC

Source last checked

30 Oct 2026, 07:10 UTC

1. Revision 2 · amended · 30 Oct 2026

   Amended from osv record GHSA-9hj8-73fh-9963

2. Revision 1 · created · 29 Oct 2026

   Published from ghsa record GHSA-9hj8-73fh-9963

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# Patch Next advisory brief: CVE-2026-115907

Advisory: zip: legacy Shrink/Reduce/Implode decoder: denial of service from attacker-controlled ZIP64 uncompressed size
IDs: CVE-2026-115907, GHSA-9hj8-73fh-9963
Record: https://patchnext.com/advisories/cve-2026-115907 (revision 2, source checked 30 Oct 2026, 07:10 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: zip 9.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io zip: affected >= 5.1.0, < 9.0.0; fixed in 9.0.0

## Suggested inspection (read-only)
- crates.io zip: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on zip.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-9hj8-73fh-9963 (GitHub-reviewed advisory GHSA-9hj8-73fh-9963 lists affected ranges: crates.io zip >=5.1.0 <9.0.0)
- Verified: https://osv.dev/vulnerability/GHSA-9hj8-73fh-9963 (OSV record GHSA-9hj8-73fh-9963 lists affected ranges: crates.io zip >=5.1.0 <9.0.0 (fixed))

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