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PatchSiren cyber security CVE debrief

CVE-2026-26740 Giflib Project CVE debrief

CVE-2026-26740 is a Buffer Overflow vulnerability in giflib v.5.2.2. The vulnerability allows a remote attacker to cause a denial of service via the EGifGCBToExtension function, which overwrites an existing Graphic Control Extension block without validating its allocated size. This issue was published on March 18, 2026, and modified on June 30, 2026. The CVSS score for this vulnerability is 8.2, indicating a high severity. The vulnerability is categorized under CWE-787. Multiple references are available, including a GitHub POC and several Red Hat errata.

Vendor
Giflib Project
Product
Giflib
CVSS
HIGH 8.2
CISA KEV
Not listed in stored evidence
Original CVE published
2026-03-18
Original CVE updated
2026-07-23
Advisory published
2026-03-18
Advisory updated
2026-07-23

Who should care

Organizations using giflib v.5.2.2 should be aware of this vulnerability, as it can be exploited remotely to cause a denial of service. The vulnerability has a high CVSS score, indicating a significant risk. Users of giflib should review their installations and consider updating to a patched version.

Technical summary

The CVE-2026-26740 vulnerability is a Buffer Overflow issue in giflib v.5.2.2. The EGifGCBToExtension function does not validate the allocated size of the Graphic Control Extension block before overwriting it, allowing a remote attacker to cause a denial of service. The vulnerability has a CVSS score of 8.2 and is categorized under CWE-787. The issue was published on March 18, 2026, and modified on June 30, 2026.

Defensive priority

High priority should be given to patching giflib v.5.2.2 installations, as the vulnerability can be exploited remotely and has a high CVSS score. Organizations should review their inventory of giflib installations and apply patches or mitigations as necessary.

Recommended defensive actions

  • Review and patch giflib v.5.2.2 installations
  • Monitor for remote exploitation attempts
  • Consider implementing compensating controls for unpatched systems
  • Review and update incident response plans
  • Monitor vendor remediation workflow for updates

Evidence notes

The CVE-2026-26740 vulnerability was published on March 18, 2026, and modified on June 30, 2026. The vulnerability has a CVSS score of 8.2 and is categorized under CWE-787. Multiple references are available, including a GitHub POC and several Red Hat errata. The vulnerability allows a remote attacker to cause a denial of service via the EGifGCBToExtension function.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-26740 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-26740

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-26740 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-26740

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://github.com/zakkanijia/POC/blob/main/giflib/giftool/giflib_giftool_gce_len_heap_oobwrite_disclosure.md

    [email protected] - Exploit, Third Party Advisory

  • Source reference

    Unverified legacy reference

    URL: https://access.redhat.com/errata/RHSA-2026:33452

    0b0ca135-0b70-47e7-9f44-1890c2a1c46c

  • Source reference

    Unverified legacy reference

    URL: https://access.redhat.com/errata/RHSA-2026:33455

    0b0ca135-0b70-47e7-9f44-1890c2a1c46c

  • Source reference

    Unverified legacy reference

    URL: https://access.redhat.com/errata/RHSA-2026:33456

    0b0ca135-0b70-47e7-9f44-1890c2a1c46c

  • Source reference

    Unverified legacy reference

    URL: https://access.redhat.com/security/cve/CVE-2026-26740

    0b0ca135-0b70-47e7-9f44-1890c2a1c46c

  • Source reference

    Unverified legacy reference

    URL: https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-26740.json

    0b0ca135-0b70-47e7-9f44-1890c2a1c46c

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.