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CVE-2026-20889: CVE-2026-20889: Heap-based Buffer Overflow in LibRaw X3F Thumbnail Parser

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CVE-2026-20889: Heap-based Buffer Overflow in LibRaw X3F Thumbnail Parser

Vulnerability ID: CVE-2026-20889
CVSS Score: 9.8
Published: 2026-04-07

CVE-2026-20889 is a critical heap-based buffer overflow in the LibRaw library triggered by integer overflows during the parsing of Sigma X3F RAW image thumbnails. The vulnerability permits unauthenticated remote code execution.

TL;DR

A critical vulnerability (CVSS 9.8) in LibRaw allows unauthenticated remote code execution via a specially crafted X3F image file. The flaw originates from an integer overflow in the thumbnail allocation routine, leading to a heap buffer overflow. Organizations must update to LibRaw 0.22.1 or apply commit b9809e410d07ca7bf408e6d036615fb34f8c47cc.

Technical Details

  • CVSS v3.1: 9.8 (Critical)
  • EPSS Score: 0.00043 (13.12%)
  • CWE ID: CWE-190
  • Attack Vector: Network
  • Exploit Status: None
  • CISA KEV: Not Listed

Affected Systems

  • Applications utilizing LibRaw for image processing pipelines
  • Web services performing automated media thumbnail generation
  • Desktop environments and document management systems supporting RAW image formats
  • LibRaw: < 0.22.1 (Fixed in: 0.22.1)

Code Analysis

Commit: b9809e4

Fix for CVE-2026-20889: Implements INT64 size calculations and stringent bounds checking in x3f_thumb_loader.

+      INT64 alloc_size = INT64(ID->columns) * INT64(ID->rows) * 3LL;
+      if ((alloc_size > 2 * checked_size) ||
+          (alloc_size > 1024LL * 1024LL * LIBRAW_MAX_THUMBNAIL_MB)) throw LIBRAW_EXCEPTION_TOOBIG;
+      if (alloc_size < 64LL)
+        throw LIBRAW_EXCEPTION_IO_CORRUPT;
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Mitigation Strategies

  • Upgrade LibRaw to version 0.22.1 or newer.
  • Apply patch commit b9809e410d07ca7bf408e6d036615fb34f8c47cc directly to local builds.
  • Filter and reject Sigma X3F RAW files at the application ingress point.
  • Deploy applications in memory-safe runtime environments with ASLR and DEP enabled.

Remediation Steps:

  1. Identify all internal applications and third-party software dependencies utilizing the LibRaw library.
  2. Verify the installed LibRaw versions utilizing package managers or software composition analysis (SCA) tools.
  3. Update LibRaw packages via the appropriate package manager (e.g., apt, yum, npm, pip) to the patched version.
  4. Recompile any static binaries linked against vulnerable versions of the LibRaw source code.
  5. Verify the integrity of image processing services post-deployment.

References

Read the full report for CVE-2026-20889 on our website for more details including interactive diagrams and full exploit analysis.

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