l-smash: Double Free
CVE-2026-110599 is a high-severity double free vulnerability in l-smash, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected l-smash versions: 2.14.5 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.24% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of l-smash you run against the affected versions below, and install the vendor's latest release.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H. Scored by CNA (vulncheck.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 6.9 | Medium | CNA (vulncheck.com) |
| CVSS 3.1 | 7.1 | High | CNA (vulncheck.com) |
Official description
L-SMASH through 2.14.5 contains a double free vulnerability in hevc_setup_first_summary() and h264_setup_first_summary() in importer/nalu_imp.c that frees borrowed codec-specific objects on error paths. Attackers can supply a crafted Annex-B elementary stream lacking a parseable SPS to lsmash_read_file() or the boxdumper, remuxer, or muxer tools, causing use-after-free, heap corruption, and crashes.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Double Free
The product calls free() twice on the same memory address.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
- Use a static analysis tool to find double free instances.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
- github.com/l-smash/l-smash/blob/v2.14.5/importer/nalu_imp.c#L1356-L1378
- github.com/l-smash/l-smash/blob/v2.14.5/importer/nalu_imp.c#L697-L715
- hackmd.io/@haind-pwn/l-smash-hevc-importer-double-free
- vulncheck.com/advisories/l-smash-through-2.14.5-double-free-in-hevc-and-h-264-importer-probe
- hackmd.io/@haind-pwn/cve-2016-20099-2026-110599-l-smash-hevc-importer-double-free
Recent Double Free vulnerabilities
- 7.8 High severity
- 9.6 Critical severity
- 7.5 High severity
- 8.5 High severity
- 9.8 Critical severity
- 7.5 High severity
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