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Fencer Intel
medium 6.0

CVE-2026-120033 json

frr: bgpd Send Hold Timer expiry bypasses the FSM, leaving a phantom Established session or crashing bgpd with Graceful Restart

published 2d ago modified 19h ago also EUVD-2026-124617

cvss
6.0
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 22%
public exploits
0
none known

Summary

In FRRouting, bgpd does not correctly close a BGP session when the Send Hold Timer (RFC 9687) expires, i.e. when a neighbor has stopped accepting data from the router for twice the hold time. The connection is closed, but bgpd still considers the session to be up. A BGP neighbor that keeps sending KEEPALIVEs but stops reading from its connection, at a time when the router has a large amount of data to send to it (for example while sending it a full routing table), can trigger this. If the neighbor announced Graceful Restart support, bgpd crashes shortly after the session is closed, taking down all BGP sessions on the router, and the neighbor can repeat this each time bgpd restarts. Otherwise, the session stays stuck in the Established state: the neighbor's routes stay installed and keep being advertised to other peers, and the neighbor cannot reconnect until an operator clears the session manually. The neighbor does not need to be malicious; an overloaded or stuck peer can trigger the same behavior. No special configuration is required: any established BGP neighbor can trigger the issue, and Graceful Restart helper mode, which leads to the crash, is enabled by default.

Patch / fix

  • frrouting frrouting 10.4.6, 10.5.6, 10.6.3, 10.7.2

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Exploit prediction

0.29% chance of exploitation in the next 30 days, higher than 22% of all scored CVEs (FIRST EPSS, 2026-11-14).

CVSS scores

assigned by version score vector
CNA 4.0 6.0 CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:H/SC:N/SI:L/SA:L/AU:N/R:A
CNA 4.0 6.0 CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:H/SC:N/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:N/R:A/V:X/RE:X/U:X

Affected products

  • frrouting frrouting

Classification

Weakness
  • CWE-617 Reachable Assertion
  • CWE-372 Incomplete Internal State Distinction

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.