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PatchSiren cyber security CVE debrief

CVE-2026-110601 saitoha CVE debrief

A heap out-of-bounds write vulnerability exists in libsixel before 1.8.7-r1 and 1.9.0 through 1.10.5 in the gif_init_frame() function. This vulnerability occurs because the GIF transparent color index is not checked against the palette size, allowing attackers to supply a crafted GIF that can write bytes past the palette buffer, causing heap corruption or crashes.

Vendor
saitoha
Product
libsixel
CVSS
MEDIUM 5.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-14
Original CVE updated
2026-10-14
Advisory published
2026-10-14
Advisory updated
2026-10-14

Who should care

Defenders responsible for systems or applications using libsixel should assess exposure and prioritize patching or upgrading to a fixed version. This vulnerability can be exploited through specially crafted GIF files, which can lead to heap corruption or crashes.

Why it matters

A heap out-of-bounds write vulnerability exists in libsixel, which can be exploited through specially crafted GIF files. Defenders should prioritize patching or upgrading to a fixed version to prevent potential heap corruption or crashes.

  • Potential heap corruption or crashes when processing specially crafted GIF files
  • Possible denial of service (DoS) or remote code execution
  • Requires verification of affected versions and exploitation
  • Defenders should prioritize patching or upgrading to a fixed version

Technical summary

The gif_init_frame() function in libsixel does not check the GIF transparent color index against the palette size, allowing for a heap out-of-bounds write vulnerability. This can be exploited by supplying a crafted GIF file with a small color table and large transparent index, processed with a background color set. Attackers can write bytes past the palette buffer, causing heap corruption or crashes. Defenders should prioritize patching or upgrading to a fixed version of libsixel, as the vulnerability can be exploited through specially crafted GIF files. Affected product deployments should be reviewed for exposure, and compensating controls should be considered for exposed systems.

Defensive priority

Defenders should prioritize patching or upgrading to a fixed version of libsixel, as the vulnerability can be exploited through specially crafted GIF files.

Recommended defensive actions

  • Patch or upgrade to a fixed version of libsixel
  • Restrict access to untrusted GIF files
  • Monitor for suspicious GIF file processing activity
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability is caused by a lack of checking for the GIF transparent color index against the palette size in the gif_init_frame() function. This can lead to heap corruption or crashes when processing specially crafted GIF files.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-110601 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-110601

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

  • CVE-2026-110601 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-110601

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

Supplemental references

  • libsixel before 1.8.7-r1 and 1.9.0 through 1.10.5 Heap Out-of-Bounds Write via GIF

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/110xxx/CVE-2026-110601.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://github.com/saitoha/libsixel/issues/220

    Supplemental source - issue-tracking

  • Source reference

    Unverified legacy reference

    URL: https://github.com/saitoha/libsixel/commit/bdbab09816eb9188429c37a50b97c5e66dfe5047

    Supplemental source - patch

  • Source reference

    Unverified legacy reference

    URL: https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1

    Supplemental source - release-notes

  • Source reference

    Unverified legacy reference

    URL: https://github.com/saitoha/libsixel/blob/v1.8.7/src/fromgif.c

    Supplemental source - technical-description

  • Source reference

    Unverified legacy reference

    URL: https://github.com/libsixel/libsixel/blob/v1.10.5/src/fromgif.c

    Supplemental source - technical-description

  • Source reference

    Unverified legacy reference

    URL: https://hackmd.io/@haind-pwn/libsixel-gif-transparent-index-oob-write

    Supplemental source - third-party-advisory

  • Source reference

    Unverified legacy reference

    URL: https://www.vulncheck.com/advisories/libsixel-before-1.8.7-r1-and-1.9.0-through-1.10.5-heap-out-of-bounds-write-via-gif

    Supplemental source - third-party-advisory

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.