CVE-2026-63626 Memory corruption in mongoose
An attacker on a PPP/PPPoE link can trigger out-of-bounds reads and heap overflows in Mongoose, potentially leading to code execution or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-63626?
CVE-2026-63626 is a high-severity memory corruption vulnerability in cesanta mongoose, published on 14 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-63626?
How do I fix CVE-2026-63626?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-63626 being exploited?
There is no known exploitation of CVE-2026-63626 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-63626, GHSA-pc66-j6r6-49x9, UBUNTU-CVE-2026-63626.