UPF crash via malformed PFCP header state
Published Sep 15, 2026 · Updated Sep 15, 2026
Denial of service in Open5GS 2.7.0 through 2.7.7 allows remote attackers to crash the UPF via crafted PFCP messages. The PFCP FAR handler partially copies a truncated or unsupported Outer Header Creation IE into zero-initialized state, creating a GTP-U node with address family zero that later reaches an assertion. Reachability requires network access to the UPF N4/PFCP interface, and the published four-message stateful sequence terminates open5gs-upfd.
Summary
What happened
Denial of service in Open5GS 2.7.0 through 2.7.7 allows remote attackers to crash the UPF via crafted PFCP messages. The PFCP FAR handler partially copies a truncated or unsupported Outer Header Creation IE into zero-initialized state, creating a GTP-U node with address family zero that later reaches an assertion. Reachability requires network access to the UPF N4/PFCP interface, and the published four-message stateful sequence terminates open5gs-upfd.
The record
- CVE
- CVE-2026-91855
- Published
- Sep 15, 2026
- Updated
- Sep 15, 2026
- Vendor
- Open5GS
- Product
- Open5GS
- Classifications
- T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 15, 2026CVE publishedPublication date reported by the CVE source.
- Sep 15, 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.
- Affected versionversion=2.7.0
- Affected versionversion=2.7.1
- Affected versionversion=2.7.2
- Affected versionversion=2.7.3
- Affected versionversion=2.7.4
- Affected versionversion=2.7.5
- Affected versionversion=2.7.6
- Affected versionversion=2.7.7
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
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.
Weakness, pattern, technique
Public exploit references
- Four-message malformed PFCP sequence reproducerfunctional · demonstrated
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Technologies
Your stack
See the directory against your own environment.
Your stack
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