Application crash via truncated GCE overwrite
Published Mar 18, 2026 · Updated Mar 18, 2026
Heap out-of-bounds write in giflib 5.2.2 allows remote attackers to crash a GIF-processing application with a crafted GIF. In egif_lib.c, EGifGCBToSavedExtension passes an existing extension buffer to EGifGCBToExtension, which writes four bytes without checking that ByteCount is four. Exploitation requires an application to rewrite a truncated Graphic Control Extension; the demonstrated consequence is process termination, not code execution.
Summary
What happened
Heap out-of-bounds write in giflib 5.2.2 allows remote attackers to crash a GIF-processing application with a crafted GIF. In egif_lib.c, EGifGCBToSavedExtension passes an existing extension buffer to EGifGCBToExtension, which writes four bytes without checking that ByteCount is four. Exploitation requires an application to rewrite a truncated Graphic Control Extension; the demonstrated consequence is process termination, not code execution.
The record
- CVE
- CVE-2026-26740
- Published
- Mar 18, 2026
- Updated
- Mar 18, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-787, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 18, 2026CVE publishedPublication date reported by the CVE source.
- Mar 18, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What is affected?
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Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- giftool truncated GCE heap-overflow PoCproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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