CVE-2026-44636Public exploit

Heap memory corruption via wrapped encoder allocation

Published May 14, 2026 · Updated May 14, 2026

Heap buffer overflow in libsixel 1.4.4 through 1.8.7-r1 allows local users to corrupt process memory via oversized image dimensions. In sixel_encode_highcolor, plain-int width and height multiplications wrap before allocation and pointer-offset calculations, producing undersized buffers followed by out-of-bounds writes. Exposure requires the HIGHCOLOR path and attacker-influenced dimensions supplied by a calling application; img2sixel is not normally a direct attack surface.

CVSS severity7.8
High
EPSS probability0.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in libsixel 1.4.4 through 1.8.7-r1 allows local users to corrupt process memory via oversized image dimensions. In sixel_encode_highcolor, plain-int width and height multiplications wrap before allocation and pointer-offset calculations, producing undersized buffers followed by out-of-bounds writes. Exposure requires the HIGHCOLOR path and attacker-influenced dimensions supplied by a calling application; img2sixel is not normally a direct attack surface.

The record

CVE
CVE-2026-44636
Published
May 14, 2026
Updated
May 14, 2026
Vendor
saitoha
Product
libsixel
Classifications
CWE-122, CWE-190
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 14, 2026CVE publishedPublication date reported by the CVE source.
  2. May 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 1.4.4, < 1.8.7-r2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

saitoha · libsixelversion=>= 1.4.4, < 1.8.7-r2

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.4GitHub, Inc.CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
CWE-190Integer Overflow or Wraparound

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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