Kamailio Grammar Rule cfg.y yyerror_at null pointer dereference

published 2025-10-27 12 mo ago modified 2026-10-19 21 d ago also EUVD-2025-36068

cvss: 3.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 14%
public exploits: 0; none known

A vulnerability has been found in Kamailio 5.5. This affects the function yyerror_at of the file src/core/cfg.y of the component Grammar Rule Handler. Such manipulation leads to null pointer dereference. The attack needs to be performed locally. The exploit has been disclosed to the public and may be used. The actual existence of this vulnerability is currently in question. This attack requires manipulating config files which might not be a realistic scenario in many cases. The vendor was contacted early about this disclosure but did not respond in any way.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 12 mo ago (2025-10-28)

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

shimo.im https://shimo.im/docs/vVqRMVMlrycMO63y/ referenced PoC, tagged "exploit" by a source, unverified
shimo.im https://shimo.im/docs/vVqRMVMlrycMO63y referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	4.8	CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
CNA	3.1	3.3	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:X/RC:R
CNA	3.0	3.3	CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:X/RC:R
CNA	2.0	1.7	AV:L/AC:L/Au:S/C:N/I:N/A:P/E:POC/RL:ND/RC:UR
CNA	4.0	1.9	CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CNA	3.1	3.3	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
NVD	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA	2.0	1.7	AV:L/AC:L/Au:S/C:N/I:N/A:P

Affected products

n/a Kamailio

Classification

Weakness

CWE-476 NULL Pointer Dereference
CWE-404 Improper Resource Shutdown or Release

References

shimo.im /docs/vVqRMVMlrycMO63y/
exploit, third-party-advisory
shimo.im /docs/vVqRMVMlrycMO63y
exploit, third-party-advisory
vuldb.com /?id.329877
vdb-entry, technical-description, third-party-advisory
vuldb.com /?ctiid.329877
signature, permissions-required, vdb-entry
vuldb.com /?submit.673241
third-party-advisory, vdb-entry
openwall.com /lists/oss-security/2025/11/02/3
related
openwall.com /lists/oss-security/2025/10/27/8
issue-tracking, mailing-list
openwall.com /lists/oss-security/2025/10/27/12
openwall.com /lists/oss-security/2025/10/27/8

Sources

CVE List CVE-2025-12207
NVD CVE-2025-12207

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary