# CVE-2026-62377 — strukturag libheif

> As of 2026-08-19, CVE-2026-62377 is a MEDIUM-severity vulnerability in strukturag libheif, CVSS v3.1 4.3, EPSS 0.4% (34.1th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-62377 as of 2026-08-19; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-08-19

## What is CVE-2026-62377?

libheif is a HEIF and AVIF file format decoder and encoder. In 1.23.0 and earlier, a crafted HEIF sequence accepted by heif_context_read_from_memory() can leave the context with no registered sequence tracks and crash when heif_context_get_track(ctx, 0) is called. HeifContext::get_track() in libheif/context.cc executes assert(has_sequence()) before its normal error handling, so assert-enabled builds abort instead of allowing the public wrapper in libheif/api/libheif/heif_sequences.cc to return null. In release builds, removing the assertion lets the track_id zero path dereference m_tracks.begin()->second on an empty map, which is undefined behavior and typically crashes. The issue is reachable through documented public APIs after parsing attacker-controlled bytes. This issue is fixed in version 1.23.1.

The record classifies CVE-2026-62377 under weakness classes [CWE-617](https://intel.threadlinqs.com/cwe/CWE-617), [CWE-908](https://intel.threadlinqs.com/cwe/CWE-908). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 48 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 4.3 — MEDIUM (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L`)
- **EPSS (FIRST):** 0.4% probability of exploitation in the next 30 days, higher than 34.1% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 5.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-08-18, last modified 2026-08-19

## Is CVE-2026-62377 being exploited?

Weaponised exploit code for CVE-2026-62377 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 46 in the Threadlinqs vulnerability feed.

- [trickest/cve](https://github.com/trickest/cve/blob/main/2026/CVE-2026-62377.md) (trickest)

## Affected products and versions

- **strukturag**: libheif

## How to fix CVE-2026-62377

No vendor patch reference has been recorded for CVE-2026-62377 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-62377

No threat campaign in the Threadlinqs corpus currently references CVE-2026-62377, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, public proof-of-concept repositories. Last verified by Threadlinqs on 2026-08-19. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com](https://github.com/strukturag/libheif/security/advisories/GHSA-9ww4-9v47-m7pj)

**Other references**

- [github.com](https://github.com/strukturag/libheif/issues/1844)
- [github.com (e1a0bc1c1ae74f8075eaca30a1cdb2b9bee698d3)](https://github.com/strukturag/libheif/commit/e1a0bc1c1ae74f8075eaca30a1cdb2b9bee698d3)
- [github.com (v1.23)](https://github.com/strukturag/libheif/releases/tag/v1.23.1)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-62377
Full detection coverage and IOCs for threats exploiting CVE-2026-62377 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp