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

Quick assessment

Affected
cesanta mongoose
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Mongoose 是一个嵌入式 Web 服务器和网络库。在 7.23 版本之前，src/l2_ppp.c 中的 ppp_handle_ipv6cp() 函数未对 16 位的 IPv6CP 长度字段进行校验，直接信任该字段而未将其与接收到的实际载荷大小进行比较。在使用 MG_ENABLE_TCPIP 和 MG_ENABLE_IPV6 的 PPP 或 PPPoE 链路上，未经认证的相邻对端在完成必要的 LCP 交换后，可以发送一个带有过大长度字段的短 Configure-Request 报文，从而导致 ppp_tx_f

CVSS 8.8 · High EPSS 0.24% · P14

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
cesanta mongoose < 7.23 affected
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I. Basic Information for CVE-2026-63626

Vulnerability Information
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Vulnerability Title
Mongoose: ppp_handle_ipv6cp() uses attacker-controlled length without bounds check — OOB read and heap overflow (PPP/PPPoE, MG_ENABLE_IPV6)
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
堆缓冲区溢出
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
cesanta mongoose < 7.23 -

II. Public POCs for CVE-2026-63626

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III. Intelligence Information for CVE-2026-63626

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Patches & Fixes for CVE-2026-63626 (1)

Vendor Pages for CVE-2026-63626 (1)

Other References for CVE-2026-63626 (1)

Same Patch Batch · cesanta · 2026-10-14 · 4 CVEs total

CVE-2026-73261 7.5 HIGH Mongoose: handle_opt() missing opts[1] > len check — 1-byte OOB read corrupts TCP MSS, sil
CVE-2026-73260 7.5 HIGH Mongoose: Out-of-bounds Read via length-counter underflow in built-in TLS X.509 DER parser
CVE-2026-73252 7.5 HIGH Mongoose: Unauthenticated remote heap out-of-bounds read in built-in TLS: off-by-one lengt

IV. Related Vulnerabilities

Same product: mongoose
Same vendor: cesanta
Same weakness: CWE-122

V. Comments for CVE-2026-63626

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