# CVE-2026-120208: libheif 1.18.0 before 1.23.3 Heap Buffer Overflow via unci Mixed-Interleave Decoder

Status: published. Published: 2026-10-31. Updated: 2026-11-02.

libheif 1.18.0 before 1.23.3 contains a heap-based buffer overflow vulnerability in unc_decoder_mixed_interleave::processTile() that allows attackers to write out of bounds by supplying chroma components with unequal bit depths. Attackers can craft a HEIF file declaring, for example, 16-bit Cb and 8-bit Cr to trigger file-controlled heap writes past the Cr plane, potentially achieving code execution in image-processing pipelines.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/strukturag/libheif/commit/9d3cd91d7b1c8c68deef6d06057ab956bcb0dfb9

## Affected products and versions

- strukturag / libheif: ≥ 1.18.0; < 1.23.3 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 7.7 (high); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: 0.36% as of 2026-11-02; percentile 30.34%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-122

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/strukturag/libheif/security/advisories/GHSA-x8r2-mggj-j6wr (CNA: VulnCheck; vendor-advisory)

- https://github.com/strukturag/libheif/commit/9d3cd91d7b1c8c68deef6d06057ab956bcb0dfb9 (CNA: VulnCheck; patch)

- https://github.com/strukturag/libheif/releases/tag/v1.23.3 (CNA: VulnCheck; release-notes)

- https://github.com/strukturag/libheif/blob/v1.23.2/libheif/codecs/uncompressed/unc_decoder_mixed_interleave.cc#L95 (CNA: VulnCheck; technical-description)

- https://www.vulncheck.com/advisories/libheif-1.18.0-before-1.23.3-heap-buffer-overflow-via-unci-mixed-interleave-decoder (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-120208; retrieved 2026-11-02; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-120208; retrieved 2026-11-02; source updated Not reported

Revision: 98a5f75a2710a80547a89eddbeb5d50d82520b09a3ee60a46139cc52c1f05fa6

Canonical: https://y2.dev/cve/CVE-2026-120208

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