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TI-2026-32536 Aliases CVE-2026-44636

libsixel: integer overflow in encoder

Priority HIGH 69CWE-122Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-122 and the CVSS impact.

Summary

libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. From to 1.8.7-r1, signed integer overflow in sixel_encode_highcolor's allocation size calculation can lead to a heap buffer overflow. The public sixel_encode entry point validates only that width and height are greater than zero, with no upper bound. width and height are multiplied as plain int when computing the allocation size for paletted_pixels and normalized_pixels. Any caller that asks libsixel to encode a pixel buffer with width times height greater than INT_MAX (about 2.15 billion) will hit a wrapped allocation size; under the right wrap, the malloc succeeds with a buffer much smaller than the encoder expects, and the encoder writes past the end of the heap allocation. This vulnerability is fixed in 1.8.7-r2.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00104 1st percentileScored 2026-11-07
Fix Fixed libsixel (saitoha): 1.8.7-r2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
saitohalibsixel1.4.4 to before 1.8.7-r21.8.7-r2Patch availableCNA
  • libsixel Vendorsaitoha Affected 1.4.4 to before 1.8.7-r2 Fixed in 1.8.7-r2 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:saitoha:libsixel:*:*:*:*:*:*:*:*1.4.4 to before 1.8.7-r2Vulnerablesaitoha
  • cpe:2.3:a:saitoha:libsixel:*:*:*:*:*:*:*:* Versions 1.4.4 to before 1.8.7-r2 Vulnerable ·saitoha

Remediation

  • Fix · CNA libsixel (saitoha) Fixed in 1.8.7-r2

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-44636

References

Advisory 1

  • TI-2026-25469 libsixel: Use-after-free in load_with_gdkpixbuf() CVSS 3.1HIGH 7.8
  • TI-2026-32537 libsixel: integer overflow in parser CVSS 3.1HIGH 7.1
  • TI-2026-25466 libsixel: Integer Overflow in write_png_to_file() leads to Heap-based Buffer Overflow CVSS 3.1HIGH 7.1
  • TI-2026-25464 libsixel: Use-After-Free in load_gif() CVSS 3.1HIGH 7.0
  • TI-2026-25467 libsixel: Use-after-free in sixel_encoder_encode_bytes() CVSS 3.1HIGH 7.3
  • TI-2026-25465 libsixel: Integer overflow leads to Out-of-bounds Read in img2sixel CVSS 3.1HIGH 7.1
See all 47 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences