CVE-2026-1521VulnerabilityPublished 28 Jan 2026Updated 23 Feb 2026

CVE-2026-1521: Open5GS · Denial of Service

Affects Open5GSSource CVE Database V5

Not known to be exploited · CVSS 6.9 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

6.9Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.6% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Open5GS	Affected =2.7.0 =2.7.1 =2.7.2 =2.7.3 =2.7.4 =2.7.5 =2.7.6	Fixed in–
GitHubopen5gs/open5gs`pkg:github/open5gs/open5gs`Other threats	Affected =2.7.0 =2.7.1 =2.7.2 =2.7.3 =2.7.4 =2.7.5 =2.7.6	Fixed in–

CPE configurations (1)

cpe:2.3:a:open5gs:open5gs:*:*:*:*:*:*:*:*

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AI-suggested

Organizations using Open5GS should immediately apply the official patch identified by commit 69b53add90a9479d7960b822fc60601d659c328b or upgrade to a version beyond 2.7.6 that includes the fix. Network administrators should restrict access to the SGWC S5-C interface by implementing network segmentation and firewall rules to limit exposure to trusted management and signaling networks only. Monitoring and anomaly detection should be enhanced to identify unusual bearer resource failure indications or repeated crashes of the SGWC process. Implementing redundancy and failover mechanisms for the SGWC component can reduce service disruption impact if an attack occurs. Regularly auditing and updating Open5GS deployments to the latest secure versions is critical. Additionally, operators should consider deploying intrusion prevention systems capable of detecting malformed S5-C messages that could trigger the vulnerability. Finally, maintaining an incident response plan specific to 5G core network components will help rapidly mitigate and recover from potential denial of service incidents.

Description

A security flaw has been discovered in Open5GS up to 2.7.6. This affects the function sgwc_s5c_handle_bearer_resource_failure_indication of the file src/sgwc/s5c-handler.c of the component SGWC. Performing a manipulation results in denial of service. The attack can be initiated remotely. The exploit has been released to the public and may be used for attacks. The patch is named 69b53add90a9479d7960b822fc60601d659c328b. It is recommended to apply a patch to fix this issue.

Impact

The primary impact of CVE-2026-1521 is denial of service against the SGWC component of Open5GS, which can cause service outages in 5G core network infrastructure. This disruption can lead to loss of connectivity for mobile users relying on the affected network, impacting voice, data, and signaling services. For mobile network operators and service providers, this can translate into degraded user experience, potential revenue loss, and damage to reputation. Since the vulnerability can be exploited remotely without authentication, attackers can target exposed SGWC interfaces to cause widespread outages. Critical infrastructure relying on Open5GS, including private 5G deployments in enterprises, industrial environments, and public networks, may face operational disruptions. Although the vulnerability does not compromise data confidentiality or integrity, the availability impact alone is significant given the essential role of the SGWC in bearer management and session continuity. The public availability of exploit code increases the urgency for mitigation to prevent opportunistic attacks.

References

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