VulnerabilityPublished 2 Feb 2026Updated 23 Feb 2026

CVE-2026-1736: Open5GS · Reachable Assertion

Affects Open5GSSource CVE Database V5

Not known to be exploited · CVSS 6.9 Medium.

Data as of 26 Oct 2026, 09:16 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 52% 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 2 Feb 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 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 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 should immediately upgrade Open5GS deployments to versions later than 2.7.6 where the vulnerability is patched. If upgrading is not immediately feasible, network administrators should implement strict filtering and validation of S11 interface traffic to block malformed or suspicious packets that could trigger the assertion. Deploying intrusion detection or prevention systems (IDS/IPS) with signatures tuned to detect exploitation attempts against this vulnerability can provide additional protection. Network segmentation should be enforced to isolate core network functions from untrusted networks, reducing exposure. Regular monitoring of SGWC logs and system health can help detect early signs of exploitation or instability. Operators should also review and harden their overall 5G core network security posture, including applying the latest security patches for all components. Coordination with Open5GS community and vendors for timely updates and advisories is recommended. Finally, conducting penetration testing and vulnerability assessments focused on 5G core components can help identify residual risks.

Description

A security vulnerability has been detected in Open5GS up to 2.7.6. Impacted is the function sgwc_s11_handle_create_indirect_data_forwarding_tunnel_request of the file /src/sgwc/s11-handler.c of the component SGWC. Such manipulation leads to reachable assertion. The attack may be launched remotely. The exploit has been disclosed publicly and may be used. A patch should be applied to remediate this issue. The issue report is flagged as already-fixed.

Impact

The primary impact of CVE-2026-1736 is the potential for denial of service against Open5GS SGWC components, which are integral to 5G core network operations. Disruption of the SGWC can interrupt user plane data forwarding, leading to degraded or lost connectivity for mobile subscribers. This can affect telecom operators' ability to maintain continuous service, impacting customer experience and potentially causing financial losses. Additionally, denial of service in core network functions can have cascading effects on dependent services and applications. Since the vulnerability can be exploited remotely without authentication, attackers can launch attacks from anywhere on the internet, increasing the threat surface. Organizations relying on Open5GS for 5G network infrastructure, including research labs, private networks, and smaller operators, are at risk. Although the vulnerability does not directly lead to data confidentiality or integrity breaches, the availability impact on critical telecom infrastructure is significant. The medium severity rating reflects these factors, emphasizing the need for timely patching to maintain network reliability.

References

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