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VulnerabilityPublished

CVE-2026-33020: saitoha libsixel · Heap-based Buffer Overflow

Affects saitoha libsixelSource CVE Database V5

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Not known to be exploited · CVSS 7.1 High : upgrade to 1.8.7-r1 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
7.1High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.8.7-r1
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade saitoha libsixel to 1.8.7-r1.

Affected software

ProductAffectedFixed in
saitohalibsixelAffected
  • <1.8.7-r1
Fixed in
  • 1.8.7-r1
GitHubsaitoha/libsixelpkg:github/saitoha/libsixelOther threatsAffected
  • =1.8.7-r1
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

This vulnerability has been fixed in libsixel version 1.8.7-r1. Users and administrators should upgrade to version 1.8.7-r1 or later to remediate this issue. No other mitigation or workaround is specified. Patch status is confirmed by the vendor's fix in 1.8.7-r1.

Description

libsixel versions prior to 1.8.7-r1 contain a heap-based buffer overflow vulnerability caused by an integer overflow in the sixel_frame_convert_to_rgb888() function. This overflow leads to an undersized heap allocation and invalid pointer arithmetic when processing large palettised images, resulting in heap corruption. An attacker can exploit this by supplying a specially crafted large palettised PNG file, potentially causing a crash or arbitrary code execution. The issue is fixed in version 1.8.7-r1.

References

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