CVE-2026-37457: An off-by-one out-of-bounds write vulnerability in the bgp_flowspec_op_decode() function (bgpd/bgp_flowspec_ut

Routine

HIGH 7.5REMOTEDOWNGRADE

CVE-2026-37457 is a high-severity flaw (CVSS 7.5) affecting frrouting. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An off-by-one out-of-bounds write vulnerability in the bgp_flowspec_op_decode() function (bgpd/bgp_flowspec_util.c) of FRRouting (FRR) stable/10.0 allows attackers to cause a Denial of Service (DoS) via supplying a crafted FlowSpec component.

Why this priority

High severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 67%)
CISA exploited list	No
Weakness	CWE-787
Published	2026-05-01
Last modified	2026-07-15

Publisher (CNA): MITRE · Vendor: frrouting

Last updated 2026-07-15 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-01 18:16 UTCPublished CVE record published
2026-07-15 02:20 UTCUpdated Record last modified

frrouting frrouting DOWNGRADE

Affected: 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

1. Check installed version

apt-cache policy frrouting || rpm -q frrouting || frrouting --version

2. No fixed release: DOWNGRADE to a release before 10.0 (Debian / Ubuntu)

apt-cache madison frrouting sudo apt install frrouting=<VERSION_BEFORE_10.0> sudo apt-mark hold frrouting

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list frrouting sudo dnf downgrade frrouting-<VERSION_BEFORE_10.0> sudo dnf versionlock add frrouting

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Advisories and coverage

Official advisories

AlmaLinux Errata: [ALSA-2026:24371] Important: frr security update 2026-07-02
AlmaLinux Errata: [ALSA-2026:24370] Important: frr10 security update 2026-07-02

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-37457?

frrouting: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-37457 being exploited?

CVE-2026-37457 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-37457 affect?

CVE-2026-37457 affects frrouting. Severity is high (CVSS 7.5). An off-by-one out-of-bounds write vulnerability in the bgp_flowspec_op_decode() function (bgpd/bgp_flowspec_util.c) of FRRouting (FRR) stable/10.0 allows attackers to cause a Denial of Service (DoS) via supplying a crafted FlowSpec componen

How urgent is CVE-2026-37457?

Priority 39/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-28532 MEDIUM 6.5 UPGRADE FRRouting before 10.5.3 contains an integer overflow vulnerability in seven OSPF Traffic Engineering and Segme
CVE-2026-37458 MEDIUM 6.5 UPGRADE Missing input validation in the MP_REACH_NLRI component of FRRouting (FRR) stable/10.0 to stable/10.6 allows a

References

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