VulnerabilityPublished 28 Jan 2026Updated 23 Feb 2026

CVE-2026-1522: Open5GS · Denial of Service

Affects Open5GSSource CVE Database V5

Public exploit available · CVSS 6.9 Medium.

Data as of 26 Oct 2026, 12:55 UTC

CVSS 4.0 base score

6.9Medium

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

EPSS: 0.7% chance of exploitation in 30 days – higher than 53% 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: evidence found.
CVSS exploit maturity: proof of concept public
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), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

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 or the CVSS exploit maturity 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 – 2.7.6 7 affected builds	Fixed in–
GitHubopen5gs/open5gs`pkg:github/open5gs/open5gs`Other threats	Affected 2.7.0 – 2.7.6 7 affected builds	Fixed in–

CPE configurations (1)

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

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AI-suggested

Organizations should immediately apply the patch identified as commit b19cf6a that fixes the vulnerability in Open5GS versions 2.7.0 through 2.7.6. If patching is not immediately possible, network administrators should restrict access to the SGWC interfaces, especially the S5 interface, using firewalls or network segmentation to limit exposure to untrusted networks. Monitoring network traffic for anomalous or malformed modify bearer response messages can help detect attempted exploitation. Deploying intrusion detection or prevention systems with signatures targeting this vulnerability can provide additional protection. Regularly updating Open5GS to the latest stable version ensures that all known vulnerabilities are addressed. Additionally, organizations should implement robust logging and alerting on core network components to quickly identify and respond to service disruptions. Conducting security assessments and penetration testing on 5G core deployments can help identify similar weaknesses proactively.

Description

A weakness has been identified in Open5GS up to 2.7.6. This vulnerability affects the function sgwc_s5c_handle_modify_bearer_response of the file src/sgwc/s5c-handler.c of the component SGWC. Executing a manipulation can lead to denial of service. The attack can be launched remotely. The exploit has been made available to the public and could be used for attacks. This patch is called b19cf6a. Applying a patch is advised to resolve this issue. The issue report is flagged as already-fixed.

Impact

The primary impact of CVE-2026-1522 is denial of service against the SGWC component of Open5GS, which can disrupt 5G core network operations. This disruption can lead to loss of connectivity for subscribers relying on the affected network, impacting voice, data, and signaling services. For organizations deploying Open5GS in production or test environments, this could result in service outages, degraded network performance, and potential reputational damage. Since the vulnerability can be exploited remotely without authentication, attackers can target exposed 5G core network interfaces to cause outages. While the vulnerability does not directly compromise confidentiality or integrity, the availability impact on critical network infrastructure can have cascading effects on dependent services and users. The risk is higher for operators and enterprises using Open5GS as part of their 5G core infrastructure, especially if the affected versions are exposed to untrusted networks without adequate perimeter defenses.

Summary

Open5GS is an open-source implementation of the 5G core network, widely used for research, testing, and some production environments. CVE-2026-1522 affects the SGWC (Serving Gateway Control) component, specifically the function sgwc_s5c_handle_modify_bearer_response located in src/sgwc/s5c-handler.c. This function handles modify bearer response messages on the S5 interface, which is critical for managing bearer sessions in the 5G core. The vulnerability arises from improper handling of these messages, allowing a remote attacker to craft malicious packets that cause the SGWC process to crash or become unresponsive, resulting in denial of service. The attack vector is network-based with no authentication or user interaction required, making it relatively easy to exploit. The vulnerability affects all Open5GS versions from 2.7.0 through 2.7.6. The issue has been publicly disclosed with a CVSS v4.0 score of 6.9 (medium severity), reflecting the moderate impact and ease of exploitation. A patch (commit b19cf6a) has been released to fix the flaw by improving input validation and error handling in the affected function. No known active exploitation campaigns have been reported, but the availability of a public exploit increases the risk of opportunistic attacks.

References

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