High severity · published Oct 14, 2026
CVE-2026-63626
Mongoose: ppp_handle_ipv6cp() uses attacker-controlled length without bounds check — OOB read and heap overflow (PPP/PPPoE, MG_ENABLE_IPV6)
8.8
CVSS
0.2%
EPSS
No
On KEV
Description
Mongoose is an embedded web server and network library. Prior to 7.23, ppp_handle_ipv6cp() in src/l2_ppp.c trusts the 16-bit IPv6CP len field without checking it against the received payload size. On a PPP or PPPoE link using MG_ENABLE_TCPIP and MG_ENABLE_IPV6, an unauthenticated adjacent peer can complete the required LCP exchange and send a short Configure-Request with an oversized length, causing ppp_tx_frame() to read beyond recv_queue.buf and write beyond tx.buf. The same length misuse can also expose adjacent heap bytes in a reply or hang the event loop through find_opt(). This issue is fixed in version 7.23.
CVSS vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 15% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MO
mongoose · cesanta
< 7.23 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-63626
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-63626
github.com
https://github.com/cesanta/mongoose/commit/751f14742dea934bec08a507ab1fecc3673d4903
github.com
https://github.com/cesanta/mongoose/releases/tag/7.23
github.com
https://github.com/cesanta/mongoose/security/advisories/GHSA-pc66-j6r6-49x9
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