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CVE-2026-27622 high CVSS 7.8

Out-of-Bounds Write in openexr (CVE-2026-27622)

Summary

Out-of-bounds write in openexr (CVE-2026-27622). Successful exploitation can lead to full system takeover. Exploitable via MultiPartInputFile. Mitigation: upgrade to 3.4.6 or later.

Original description

The description as published by the source.

Summary

Function: CompositeDeepScanLine::readPixels, reachable from high-level multipart deep read flows (MultiPartInputFile + DeepScanLineInputPart + CompositeDeepScanLine).

Vulnerable lines (src/lib/OpenEXR/ImfCompositeDeepScanLine.cpp):

  • total_sizes[ptr] += counts[j][ptr]; (line ~511)
  • overall_sample_count += total_sizes[ptr]; (line ~514)
  • samples[channel].resize (overall_sample_count); (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 generic_unpack_deep_pointers (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 out-of-bounds.

Tested on: OpenEXR 4.0.0-dev (commit 83449669402080874b25ff1fa740649a9e6ea064) but this code has existed since v2.3.0

Steps to reproduce

composite_deepscanline_poc_bundle.patch

PoC files used:

  • Writer/generator: poc/composite_deep_scanline_e2e_compressed_poc.cpp
  • Minimal high-level reader harness: poc/simple_exr_reader.cpp

The reader harness intentio…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-27622 has been found in openexr.
Attackers can target a specific entry point like MultiPartInputFile over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 7.8/10.
What to do: upgrade openexr to 3.4.6 or later.
If unsure, ask your IT team or search "openexr CVE-2026-27622" on the vendor's site.

CVE-2026-27622 (openexr) — CWE-787 / CVSS v3 7.8
Attack vector: local / unauthenticated
Attack surface: MultiPartInputFile / DeepScanLineInputPart / CompositeDeepScanLine / generic_unpack_deep_pointers
Patched: 3.4.6 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

Out-of-bounds write (CWE-787) exists in openexr. Attackers reach the vulnerable code path via MultiPartInputFile without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of openexr. Attack surface: MultiPartInputFile / DeepScanLineInputPart / CompositeDeepScanLine / generic_unpack_deep_pointers.

🔥 Severity

Severity: High (CVSS 7.8/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 3.4.6.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'openexr' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'openexr' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で openexr を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade openexr to 3.4.6

    ステージング環境で 3.4.6 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

PyPI openexr
[{"type":"ECOSYSTEM","events":[{"introduced":"3.4.0"},{"fixed":"3.4.6"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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