Open5GS SMF gsm-build.c gsm_build_pdu_session_establishment_accept denial of service

published 2026-05-11 5 mo ago modified 2026-07-23 3 mo ago also EUVD-2026-29023

cvss: 4.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits: 0; none known

A vulnerability was detected in Open5GS up to 2.7.7. This affects the function gsm_build_pdu_session_establishment_accept of the file /src/smf/gsm-build.c of the component SMF. The manipulation results in denial of service. The attack can be launched remotely. The exploit is now public and may be used. The project was informed of the problem early through an issue report but has not responded yet.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 5 mo ago (2026-05-12)

Exploit prediction

0.46% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/open5gs/open5gs/issues/4447 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	5.3	CVSS:4.0/AV:N/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	4.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:X/RC:R
CNA	3.0	4.3	CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:X/RC:R
CNA	2.0	4.0	AV:N/AC:L/Au:S/C:N/I:N/A:P/E:POC/RL:ND/RC:UR
CNA	4.0	2.1	CVSS:4.0/AV:N/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	4.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
NVD	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA	2.0	4.0	AV:N/AC:L/Au:S/C:N/I:N/A:P

Affected products

n/a Open5GS

Classification

Weakness

CWE-404 Improper Resource Shutdown or Release

References

github.com /open5gs/open5gs/issues/4447
exploit, issue-tracking
vuldb.com /vuln/362563
vdb-entry, technical-description, third-party-advisory
vuldb.com /vuln/362563/cti
signature, permissions-required, vdb-entry
vuldb.com /submit/808483
third-party-advisory, vdb-entry
github.com /open5gs/open5gs/
product

Sources

CVE List CVE-2026-8266
NVD CVE-2026-8266

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