CVE-2026-49837

MEDIUMPre-NVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 83% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.9Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

GoBGP is an open source Border Gateway Protocol (BGP) implementation in the Go Programming Language. Versions prior to 4.6.0 contain a BGP OPEN capability parsing issue where several concrete capability decoders may parse data from the full remaining capability buffer instead of the slice bounded by the declared capability length, CapLen. A malformed BGP OPEN message can cause bytes from a following capability to be interpreted as part of the current capability. The most security-relevant case is the 4-octet AS capability, where a capability with CapLen == 0 may cause the parser to read bytes from the following capability as the 4-octet AS value. This parsed value may later affect peer AS validation during BGP session establishment. Version 4.6.0 patches the issue.

CVSS v3
5.9
EG Score
5.9(medium)
EG Risk
27(Track)
EG Risk 27/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity59% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
17%
KEV
Not listed

Published

July 9, 2026

Last Modified

September 16, 2026

Advisory Details (2)

Auto-updated Sep 10, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit.
github_commit

commit f02ca397821f (osrg/gobgp)

Fix landed in osrg/gobgp commit f02ca397821f — awaiting tagged release

https://github.com/osrg/gobgp/commit/f02ca397821f6ca182ef4eb492c3cbc459552d7c
github Patch Available🟡 PoC Available

BGP OPEN capability parser may read capability values outside declared CapLen boundaries · Advisory · osrg/gobgp · GitHub

https://github.com/osrg/gobgp/security/advisories/GHSA-gjrg-jjr3-56cm

Vendor Advisories for CVE-2026-49837(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
gobgp2.25.0-2 ... 4.6.0-1 (27 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
gobgp3.10.0-1 ... 4.8.0-2~exp1 (27 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
gobgp3.36.0-2 ... 4.8.0-2~exp1 (12 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
gobgp3.36.0-2, 4.3.0-1, 4.4.0-1, 4.5.0-1, 4.5.0-1~bpo13+14.6.0-1—
Go(1)
PackageVulnerable rangeFixed inDependents
github.com/osrg/gobgp/v4—4.6.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 10× in last 7d / 13× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 05:26 UTCEG score recompute
  3. 2026-09-16 14:08 UTCEPSS rescore
  4. 2026-09-16 13:48 UTCEG score recompute
  5. 2026-09-16 05:15 UTCEPSS rescore
  6. 2026-09-15 16:35 UTCEG score recompute
  7. 2026-09-15 15:25 UTCEG score recompute
  8. 2026-09-14 08:50 UTCEG score recompute
  9. 2026-09-13 16:47 UTCEPSS rescore
  10. 2026-09-13 08:16 UTCEG score recompute
  11. 2026-09-12 03:18 UTCEG score recompute
  12. 2026-09-11 14:53 UTCEPSS rescore
  13. 2026-09-10 22:20 UTCEG score recompute
  14. 2026-07-30 14:50 UTCEG score recompute
  15. 2026-07-26 12:14 UTCEG score recompute
  16. 2026-07-23 03:18 UTCEG score recompute
  17. 2026-07-09 23:46 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-49837?
CVE-2026-49837 is a medium vulnerability published on July 9, 2026. GoBGP is an open source Border Gateway Protocol (BGP) implementation in the Go Programming Language. Versions prior to 4.6.0 contain a BGP OPEN capability parsing issue where several concrete capability decoders may parse data from the full remaining capability buffer instead of the slice bounded…
When was CVE-2026-49837 disclosed?
CVE-2026-49837 was first published in the National Vulnerability Database on July 9, 2026, with the most recent update on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-49837 actively exploited?
CVE-2026-49837 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 82.5% of all scored CVEs.
What is the CVSS score of CVE-2026-49837?
CVE-2026-49837 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-49837?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-49837, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-49837

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