CVE-2026-3950 — strukturag libheif stsz/stts track.cc load out-of-bounds
A vulnerability was identified in strukturag libheif up to 1.21.2. This impacts the function Track::load of the file libheif/sequences/track.cc of the component stsz/stts. The manipulation leads to out-of-bounds read. The attack needs to be performed locally. The exploit is publicly available and might be used. Applying a patch is the recommended action to fix this issue. The patch available is inofficial and not approved yet.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.2% (30-day exploitation probability)+1
- CISA SSVC: exploitation "poc"+5
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Strukturag Libheif).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Strukturag | Libheif | version 1.21.0version 1.21.1version 1.21.2 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 4.8 | CVSS 4.0 | Medium | — | — | VulDB via CVE Program (cve.org) e CISA ADP |
| 1.9 | CVSS 4.0 | Low | — | — | cna@vuldb.com via NIST National Vulnerability Database |
| 3.3 | CVSS 3.1 | Low | 1.8 | 1.4 | cna@vuldb.com via NIST National Vulnerability Database |
| 3.3 | CVSS 3.1 | Low | — | — | VulDB via CVE Program (cve.org) e CISA ADP |
| 3.3 | CVSS 3.0 | Low | — | — | VulDB via CVE Program (cve.org) e CISA ADP |
| 1.7 | CVSS 2.0 | Low | 3.1 | 2.9 | cna@vuldb.com via NIST National Vulnerability Database |
| 1.7 | CVSS 2.0 | Low | — | — | VulDB via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L (score shown at the top: cna@vuldb.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
CWE-119 · Buffer Errors (Improper Restriction of Operations within Memory Bounds)
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.19%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · strukturag/libheif
- SSVC assessment updated
- Record published
- CVSS changed · 3.3
- Source status changed · → Deferred
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
7 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-49271 libheif: Wrapped icef compressed-unit range check causes out-of-bounds read in uncompressed HEIF decoder Jun 19, 2026
- High CVE-2026-41071 libheif: Heap buffer over-read in SampleAuxInfoReader via crafted HEIF sequence file with mismatched saiz sample count May 22, 2026
- Medium CVE-2026-41069 libheif allows Out-of-bounds vector access leading to invalid dereference (DoS) May 22, 2026
- High CVE-2026-32741 libheif has a heap buffer overflow in decode_mask_image() May 19, 2026
- High CVE-2026-32882 libheif: Heap Buffer OOB Read in overlay compositing due to wrong alpha stride May 19, 2026
- Medium CVE-2026-32814 libheif: Uninitialized Heap Memory Information Leak via Failed Grid Tiles May 19, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-3950 is "strukturag libheif stsz/stts track.cc load out-of-bounds", rated Low. It affects Libheif (Strukturag); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 3.3 describes technical severity. EPSS 0.19% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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