CVE-2026-91855

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreHIGH confidence

Score 5.3 from GitHub Security Advisory published 2026-09-15. a secondary CVSS source baseline 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 5 sources updated this weekElevated
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.3Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

A security flaw has been discovered in Open5GS up to 2.7.7. Affected by this vulnerability is an unknown functionality of the file lib/pfcp/handler.c of the component PFCP Message Handler. Performing a manipulation results in denial of service. Remote exploitation of the attack is possible. The exploit has been released to the public and may be used for attacks. The patch is named 028e1dbb5e3271035ccee906ef417a97fc523f71. Applying a patch is the recommended action to fix this issue. CVE-2025-29339 describes a different assertion failure vulnerability in Open5GS UPF.

CVSS v3
5.3
EG Score
5.3(high)
EG Risk
55(Attend)
EG Risk 55/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity53% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
36%
KEV
Not listed

Published

September 15, 2026

Last Modified

September 16, 2026

Advisory Details (3)

Auto-updated Sep 15, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic

GitHub - open5gs/open5gs: Open5GS is a C-language Open Source implementation for 5G Core and EPC, i.e. the core network of LTE/NR network (Release-19) · GitHub

https://github.com/open5gs/open5gs/
github_commit

commit 028e1dbb5e32 (open5gs/open5gs)

Fix landed in open5gs/open5gs commit 028e1dbb5e32 — awaiting tagged release

https://github.com/open5gs/open5gs/commit/028e1dbb5e3271035ccee906ef417a97fc523f71
generic

[Bug]: UPF crash in stateful PFCP sequence with repeated malformed Outer Header Creation · Issue #4699 · open5gs/open5gs · GitHub

https://github.com/open5gs/open5gs/issues/4699

Vendor Advisories for CVE-2026-91855(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 19× in last 7d / 19× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-19 11:45 UTCEG score recompute
  2. 2026-09-19 11:44 UTCGHSA enrichment
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-18 12:25 UTCEG score recompute
  5. 2026-09-18 12:25 UTCGHSA enrichment
  6. 2026-09-17 19:32 UTCEPSS rescore
  7. 2026-09-17 13:05 UTCEG score recompute
  8. 2026-09-17 13:05 UTCGHSA enrichment
  9. 2026-09-16 14:09 UTCEPSS rescore
  10. 2026-09-16 13:44 UTCGHSA enrichment
  11. 2026-09-15 18:33 UTCEG score recompute
  12. 2026-09-15 18:33 UTCGHSA enrichment
  13. 2026-09-15 18:31 UTCNVD updateCVSS v4 → 5.5
  14. 2026-09-15 17:48 UTCEG score recompute
  15. 2026-09-15 17:47 UTCMITRE cvelistV5CVSS v4 → 6.9
  16. 2026-09-15 17:32 UTCEG score recompute
  17. 2026-09-15 17:31 UTCNVD updateCVSS v4 → 5.5
  18. 2026-09-15 16:53 UTCEG score recompute
  19. 2026-09-15 16:52 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-91855?
CVE-2026-91855 is a medium vulnerability published on September 15, 2026. A security flaw has been discovered in Open5GS up to 2.7.7. Affected by this vulnerability is an unknown functionality of the file lib/pfcp/handler.c of the component PFCP Message Handler. Performing a manipulation results in denial of service. Remote exploitation of the attack is possible. The…
When was CVE-2026-91855 disclosed?
CVE-2026-91855 was first published in the National Vulnerability Database on September 15, 2026, with the most recent update on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-91855 actively exploited?
CVE-2026-91855 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 64.2% of all scored CVEs.
What is the CVSS score of CVE-2026-91855?
CVE-2026-91855 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-91855?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-91855, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-91855

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