High 8.8Published Oct 14, 2026

CVE-2026-63626Mongoose: ppp_handle_ipv6cp() uses attacker-controlled length without bounds check — OOB read and heap overflow (PPP/PPPoE, MG_ENABLE_IPV6)

Updated under an hour ago (2026-10-19 08:30 UTC)

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It affects cesanta mongoose. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.24%, higher than 14% of scored CVEs.

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Exploited in the last 30 days

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: 8.8 HIGH (v3.1, CNA)CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-122, CWE-125
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.24% (percentile 14)
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Oct 15, 2026
First seen by InfoSec Signals: Oct 14, 2026

Affected products

Affected products

cesanta mongoose cesanta:mongoose (from the name)	before 7.23	CNA record

References

https://github.com/cesanta/mongoose/security/advisories/GHSA-pc66-j6r6-49x9x-refsource-confirm
https://github.com/cesanta/mongoose/commit/751f14742dea934bec08a507ab1fecc3673d4903x-refsource-misc
https://github.com/cesanta/mongoose/releases/tag/7.23x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.