CVE-2025-11678: warmcat libwebsocket · Stack-based Buffer Overflow
Affects warmcat libwebsocketSource CVE Database V5
Not known to be exploited · CVSS 7.5 High.
Data as of 26 Oct 2026, 06:26 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/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 2026-10-26.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| warmcat libwebsocket | Affected
| Fixed in– |
AI-suggested
1. Disable the LWS_WITH_SYS_ASYNC_DNS flag during compilation if asynchronous DNS resolution is not essential for your application to eliminate the vulnerable code path. 2. Monitor network traffic for unusual DNS responses, especially those with abnormally long labels or unexpected transaction IDs, to detect potential exploitation attempts. 3. Implement network segmentation and DNS traffic encryption (e.g., DNS over TLS or DNS over HTTPS) to reduce the risk of DNS traffic sniffing and manipulation. 4. Apply patches or updates from the libwebsockets project as soon as they become available to address this vulnerability directly. 5. Conduct thorough code audits and penetration testing on applications using libwebsockets to identify and remediate any related vulnerabilities. 6. Employ runtime protections such as stack canaries, address space layout randomization (ASLR), and control flow integrity (CFI) to mitigate exploitation impact. 7. Educate development and security teams about the risks of enabling asynchronous DNS features without proper safeguards.
Description
Stack-based Buffer Overflow in lws_adns_parse_label in warmcat libwebsockets allows, when the LWS_WITH_SYS_ASYNC_DNS flag is enabled during compilation, to overflow the label_stack, when the attacker is able to sniff a DNS request in order to craft a response with a matching id containing a label longer than the maximum.