Low

CVE-2026-5123 — osrg GoBGP bgp.go DecodeFromBytes off-by-one

A weakness has been identified in osrg GoBGP up to 4.3.0. This impacts the function DecodeFromBytes of the file pkg/packet/bgp/bgp.go. Executing a manipulation of the argument data[1] can lead to off-by-one. The attack may be launched remotely. Attacks of this nature are highly complex. The exploitability is said to be difficult. This patch is called 67c059413470df64bc20801c46f64058e88f800f. A patch should be applied to remediate this issue.

Published Mar 30, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: VulDB

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.7% (30-day exploitation probability)+8

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.68%

ahead of 51% of scored CVEs · Oct 14, 2026

Affects

Osrg

Gobgp

CVSS base

3.7

Low · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented patch — github.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Osrg Gobgp).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
Apply the fixed version or the patch documented under Remediation.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Osrg	Gobgp	< 4.4.0	Vulnerable	NIST National Vulnerability Database
Osrg	Gobgp	version 4.0version 4.1version 4.2version 4.3.0	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

High

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

Low

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
6.3	CVSS 4.0	Medium	—	—	cna@vuldb.com via NIST National Vulnerability Database
6.3	CVSS 4.0	Medium	—	—	VulDB via CVE Program (cve.org) e CISA ADP
3.7	CVSS 3.1	Low	2.2	1.4	cna@vuldb.com via NIST National Vulnerability Database
3.7	CVSS 3.1	Low	—	—	VulDB via CVE Program (cve.org) e CISA ADP
3.7	CVSS 3.0	Low	—	—	VulDB via CVE Program (cve.org) e CISA ADP
2.6	CVSS 2.0	Low	4.9	2.9	cna@vuldb.com via NIST National Vulnerability Database
2.6	CVSS 2.0	Low	—	—	VulDB via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L (score shown at the top: cna@vuldb.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-189

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.68%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · osrg/gobgp
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
Fix documented
Oct 13, 2026 · NIST National Vulnerability Database
CVSS changed · 3.7
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Mar 30, 2026 · VulDB

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

6 on the record

github.com/osrg/gobgp/commit/67c059413470df64bc20801c46f64058e88f800f
Patch, patch, NIST National Vulnerability Database
github.com/osrg/gobgp/pull/3342
Issue Tracking, issue-tracking, patch, NIST National Vulnerability Database
vuldb.com/vuln/354155
Third Party Advisory, VDB Entry, vdb-entry, technical-description, NIST National Vulnerability Database
vuldb.com/submit/780179
Third Party Advisory, VDB Entry, third-party-advisory, NIST National Vulnerability Database
vuldb.com/vuln/354155/cti
Permissions Required, VDB Entry, signature, permissions-required, NIST National Vulnerability Database
github.com/osrg/gobgp/
Product, product, NIST National Vulnerability Database

Elsewhere on this site

Osrg
every CVE for this vendor

CWE-189
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-42285 GoBGP: Panic in AdjRib.Update via malformed BGP Update message (Nil Pointer Dereference) May 7, 2026
High CVE-2026-41642 GoBGP: Remote Denial of Service (Panic) via Malformed Well-known Path Attribute May 7, 2026
High CVE-2026-41643 GoBGP: Remote Denial of Service (Panic) in UpdatePathAttrs4ByteAs via Malformed BGP UPDATE May 7, 2026
High CVE-2026-37461 Out-of-bounds Read in Osrg Gobgp May 4, 2026
High CVE-2026-7736 osrg GoBGP mrt.go parseRibEntry integer underflow May 4, 2026
High CVE-2026-7737 osrg GoBGP BMP Parser bmp.go BMPStatisticsReport.ParseBody out-of-bounds May 4, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-5123 is "osrg GoBGP bgp.go DecodeFromBytes off-by-one", rated Low. It affects Gobgp (Osrg); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 3.7 describes technical severity. EPSS 0.68% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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