CVE-2025-24934 json
SO_REUSEPORT_LB breaks connect(2) for UDP sockets
published last yr. modified 21d ago also EUVD-2025-35613
- cvss
- 5.4
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 11%
- public exploits
- 0
- none known
Summary
Software which sets SO_REUSEPORT_LB on a socket and then connects it to a host will not directly observe any problems. However, due to its membership in a load-balancing group, that socket will receive packets originating from any host. This breaks the contract of the connect(2) and implied connect via sendto(2), and may leave the application vulnerable to spoofing attacks.
The kernel failed to check the connection state of sockets when adding them to load-balancing groups. Furthermore, when looking up the destination socket for an incoming packet, the kernel will match a socket belonging to a load-balancing group even if it is connected, in violation of the contract that connected sockets are only supposed to receive packets originating from the connected host.
Patch / fix
- FreeBSD FreeBSD p1, p5, p6
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Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- last yr.
Exploit prediction
0.22% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 5.4 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N |
| CNA | 3.1 | 5.4 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N |
Affected products
- FreeBSD FreeBSD
Classification
- Weakness
-
- CWE-488 Exposure of Data Element to Wrong Session
References
-
security.freebsd.org
/advisories/FreeBSD-SA-25:09.netinet.asc
vendor-advisory
-
usenix.org
/system/files/conference/usenixsecurity26/sec26_prepub_ben-simhon.pdf
technical-description
Sources
- CVE List CVE-2025-24934
- NVD CVE-2025-24934
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