VulnerabilityPublished 30 Mar 2026

CVE-2026-5122: osrg GoBGP · Improper Access Controls

Affects osrg GoBGPSource CVE Database V5

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Not known to be exploited · CVSS 6.3 Medium.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score

6.3Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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: High: The successful attack depends on the evasion or circumvention of security-enhancing techniques in place that would otherwise hinder the attack. These include: Evasion of exploit mitigation techniques, for example, circumvention of address space randomization (ASLR) or data execution prevention (DEP) must be performed for the attack to be successful; Obtaining target-specific secrets. The attacker must gather some target-specific secret before the attack can be successful. A secret is any piece of information that cannot be obtained through any amount of reconnaissance. To obtain the secret the attacker must perform additional attacks or break otherwise secure measures (e.g. knowledge of a secret key may be needed to break a crypto channel). This operation must be performed for each attacked target.
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: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within 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.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 30 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 29 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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
osrgGoBGP	Affected 4.0 – 4.3.0 4 affected builds	Fixed in–
Gogithub.com/osrg/gobgp`pkg:golang/github.com/osrg/gobgp`Other threats	Affected 4.0 – 4.3.0 4 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Apply the official patch identified by commit 2b09db390a3d455808363c53e409afe6b1b86d2d immediately to all affected GoBGP instances (versions 4.0 through 4.3.0). In addition, network administrators should: 1) Restrict BGP session establishment to trusted peers only, using access control lists and firewall rules to limit exposure. 2) Monitor BGP session logs for unusual OPEN message activity or anomalies in domainNameLen values. 3) Employ network segmentation to isolate BGP routers from untrusted networks. 4) Use BGP session authentication mechanisms such as TCP MD5 signatures or TCP-AO to reduce risk of unauthorized session manipulation. 5) Regularly update and audit GoBGP deployments to ensure no outdated versions remain. 6) Implement anomaly detection systems focused on BGP traffic to identify potential exploitation attempts early.

Description

A security flaw has been discovered in osrg GoBGP up to 4.3.0. This affects the function DecodeFromBytes of the file pkg/packet/bgp/bgp.go of the component BGP OPEN Message Handler. Performing a manipulation of the argument domainNameLen results in improper access controls. The attack may be initiated remotely. A high degree of complexity is needed for the attack. The exploitability is reported as difficult. The patch is named 2b09db390a3d455808363c53e409afe6b1b86d2d. It is suggested to install a patch to address this issue.

Impact

The vulnerability impacts the confidentiality and integrity of BGP sessions managed by GoBGP. Successful exploitation could allow attackers to manipulate BGP OPEN message processing, potentially leading to unauthorized access or disruption of BGP session establishment. This could result in routing instability, traffic interception, or denial of service in networks relying on GoBGP for routing. Given BGP's role in internet backbone routing and enterprise networks, exploitation could affect network availability and trustworthiness. However, the high complexity and lack of known exploits reduce immediate risk. Organizations operating critical infrastructure or large-scale networks using GoBGP are at higher risk, as exploitation could impact network routing and connectivity on a broader scale.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Mar 2026, 15:08 UTC

Technical details

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