CVE-2026-63626Public exploitHinoki check available

Heap corruption via unchecked IPv6CP length

Published Oct 14, 2026 · Updated Oct 14, 2026

Heap overflow in Cesanta Mongoose 7.22 and earlier allows attackers to corrupt memory via IPv6CP frames on a PPP or PPPoE link. The ppp_handle_ipv6cp() function in src/l2_ppp.c passes an unchecked packet length to ppp_tx_frame(), reading beyond recv_queue.buf and writing beyond tx.buf. An unauthenticated adjacent peer must complete LCP negotiation against a build with MG_ENABLE_TCPIP and MG_ENABLE_IPV6 enabled; malformed frames also disclose heap bytes or hang the event loop through find_opt().

CVSS severity8.8
High
EPSS probability0.24%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Heap overflow in Cesanta Mongoose 7.22 and earlier allows attackers to corrupt memory via IPv6CP frames on a PPP or PPPoE link. The ppp_handle_ipv6cp() function in src/l2_ppp.c passes an unchecked packet length to ppp_tx_frame(), reading beyond recv_queue.buf and writing beyond tx.buf. An unauthenticated adjacent peer must complete LCP negotiation against a build with MG_ENABLE_TCPIP and MG_ENABLE_IPV6 enabled; malformed frames also disclose heap bytes or hang the event loop through find_opt().

The record

CVE
CVE-2026-63626
Published
Oct 14, 2026
Updated
Oct 14, 2026
Vendor
Cesanta
Product
Mongoose
Classifications
CWE-125, CWE-122, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 7.23

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Cesanta · Mongooseversion=< 7.23

Published CVSS scores

8.8CesantaCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-125Out-of-bounds Read
CWE-122Heap-based Buffer Overflow
T1499Endpoint Denial of Service

Public exploit references

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Technologies

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