CVE-2025-11680: warmcat libwebsockets · Out-of-bounds Write
Affects warmcat libwebsocketsSource CVE Database V5
Not known to be exploited · CVSS 5.9 Medium.
Data as of 26 Oct 2026, 12:54 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 33% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 20 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| warmcat libwebsockets | Affected
| Fixed in– |
AI-suggested
- Immediately audit all deployments of libwebsockets version 4.0 to identify usage of the LWS_WITH_UPNG flag and HTML display stack.
- If possible, disable the LWS_WITH_UPNG flag or avoid using the HTML display stack until a patch is available.
- Implement strict input validation and filtering on PNG files processed by libwebsockets to detect and block images with suspiciously large width values.
- Employ network-level protections such as web application firewalls (WAFs) to detect and block malicious PNG payloads from untrusted sources.
- Monitor vendor announcements and subscribe to security advisories for updates or patches addressing this vulnerability.
- Consider isolating or sandboxing applications using libwebsockets to limit the impact of potential crashes or memory corruption.
- Conduct penetration testing and fuzzing on affected systems to identify if the vulnerability can be exploited in the specific environment.
- Prepare incident response plans to quickly address potential exploitation attempts.
- Engage with vendors or open-source maintainers to accelerate patch development and deployment.
Description
Out-of-bounds Write in unfilter_scanline in warmcat libwebsockets allows, when the LWS_WITH_UPNG flag is enabled during compilation and the HTML display stack is used, to write past a heap allocated buffer possibly causing a crash, when the user visits an attacker controlled website that contains a crafted PNG file with a big width value that causes an integer overflow which value is used for determining the size of a heap allocation.