CVE-2026-3949Public exploit

Application crash via unchecked VVC NAL length

Published Mar 11, 2026 · Updated Mar 11, 2026

Out-of-bounds read in libheif 1.21.0 through 1.21.2 allows local users to crash VVC-enabled image-processing applications. vvdec_push_data2 reads a four-byte NAL size from frame data, then copies that declared number of bytes without checking it against the remaining frame size. Reachability requires a build with the optional vvdec VVC decoder and processing a crafted HEIF file; the demonstrated result is an application crash.

CVSS severity3.3
Low
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in libheif 1.21.0 through 1.21.2 allows local users to crash VVC-enabled image-processing applications. vvdec_push_data2 reads a four-byte NAL size from frame data, then copies that declared number of bytes without checking it against the remaining frame size. Reachability requires a build with the optional vvdec VVC decoder and processing a crafted HEIF file; the demonstrated result is an application crash.

The record

CVE
CVE-2026-3949
Published
Mar 11, 2026
Updated
Mar 11, 2026
Vendor
Struktur AG
Product
libheif
Classifications
CWE-125, CWE-119
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 11, 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=1.21.0
  2. Affected versionversion=1.21.1
  3. Affected versionversion=1.21.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Struktur AG · libheifversion=1.21.0; version=1.21.1; version=1.21.2

Published CVSS scores

1.9VulDBCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
1.7VulDBAV:L/AC:L/Au:S/C:N/I:N/A:P
3.3VulDBCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-125Out-of-bounds Read
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer

Public exploit references

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Technologies

Your stack

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Your stack

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