OpenEXR's CompositeDeepScanLine integer-overflow leads to heap OOB write

Exploitation

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

CVSS 4.0

8.4 · CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-27622: 0.24% estimated exploitation activity in the next 30 days; percentile 15.38 (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 Function: CompositeDeepScanLine::readPixels, reachable from high-level multipart deep read flows (MultiPartInputFile + DeepScanLineInputPart + CompositeDeepScanLine). Vulnerable lines (src/lib/OpenEXR/ImfCompositeDeepScanLine.cpp): - totalsizes[ptr] += counts[j][ptr]; (line ~511) - overallsamplecount += totalsizes[ptr]; (line ~514) - samples[channel].resize (overallsamplecount); (line ~535) Impact: 32-bit sample-count accumulation wrap leads to undersized allocation, then decode writes with true sample volume, causing heap OOB write in genericunpackdeeppointers (src/lib/OpenEXRCore/unpack.c:1374) (DoS/Crash, memory corruption/RCE). Attack scenario: - Attacker provides multipart deep EXR with many parts and very large sample counts per pixel. - Uses compression (RLE/ZIPS) to keep file size relatively small vs decode pressure. - The overflow happens in composite sample accounting (unsigned int), while pointer progression for decode uses larger counters and reaches…

Published by the source

2 Mar 2026, 18:30 UTC

Last modified by the source

13 Jul 2026, 16:43 UTC

Source last checked

26 Oct 2026, 13:36 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-cr4v-6jm6-4963

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-cr4v-6jm6-4963

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-27622

Advisory: OpenEXR's CompositeDeepScanLine integer-overflow leads to heap OOB write
IDs: CVE-2026-27622, GHSA-cr4v-6jm6-4963
Record: https://patchnext.com/advisories/cve-2026-27622 (revision 3, source checked 26 Oct 2026, 13:36 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: openexr 3.4.6, 3.3.8, 3.2.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI openexr: affected >= 2.3.0, < 3.2.6; >= 3.3.0, < 3.3.8; >= 3.4.0, < 3.4.6; fixed in 3.4.6, 3.3.8, 3.2.6

## Suggested inspection (read-only)
- `python -m pip show openexr`: prints the installed version. Run with the environment that serves production active.

## 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 openexr.
- 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://osv.dev/vulnerability/GHSA-cr4v-6jm6-4963 (OSV record GHSA-cr4v-6jm6-4963 lists affected ranges: PyPI openexr >=2.3.0 =3.3.0 =3.4.0 <3.4.6 (fixed))
- Verified: https://github.com/advisories/GHSA-cr4v-6jm6-4963 (GitHub-reviewed advisory GHSA-cr4v-6jm6-4963 lists affected ranges: PyPI openexr >=2.3.0 =3.3.0 =3.4.0 <3.4.6)

Commands are suggestions: review each one before running it.