Bug 2552783 (CVE-2026-63626)

Summary: CVE-2026-63626 mongoose: Mongoose: Buffer overflow via oversized IPv6CP packet length
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Mongoose. An unauthenticated adjacent attacker can exploit this issue by sending a specially crafted Point-to-Point Protocol (PPP) packet containing an oversized length field during IPv6 Control Protocol (IPv6CP) negotiation. This lack of bounds validation causes out-of-bounds memory read and write operations, which can lead to memory corruption, sensitive information disclosure, or a denial of service (DoS).
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Bug Depends On: 2553621    
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Description OSIDB Bzimport 2026-10-14 18:42:32 UTC 
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.