CVE-2026-45859
What it is
In the Linux kernel, the following vulnerability has been resolved: netfilter: nfnetlink_queue: do shared-unconfirmed check before segmentation Ulrich reports a regression with nfqueue: If an application did not set the 'F_GSO' capability flag and a gso packet with an unconfirmed nf_conn entry is received all packets are now dropped instead of queued, because the check happens after skb_gso_segment(). In that case, we did have exclusive ownership of the skb and its associated conntrack entry. The elevated use count is due to skb_clone happening via skb_gso_segment(). Move the check so that its peformed vs. the aggregated packet. Then, annotate the individual segments except the first one so we can do a 2nd check at reinject time. For the normal case, where userspace does in-order reinjects, this avoids packet drops: first reinjected segment continues traversal and confirms entry, remaining segments observe the confirmed entry. While at it, simplify nf_ct_drop_unconfirmed(): We only care about unconfirmed entries with a refcnt > 1, there is no need to special-case dying entries. This only happens with UDP. With TCP, the only unconfirmed packet will be the TCP SYN, those aren't aggregated by GRO. Next patch adds a udpgro test case to cover this scenario.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Exploit odds
- 0.7% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.7% in the next 30 days (EPSS).
- Severity: 7.5 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.7% · EPSS, next 30 days
- Weakness
- CWE-400 · Uncontrolled resource consumption
- Record status
- Modified
Affected
- Linux Kernel < 5.16
- Linux Kernel < 6.2
- Linux Kernel < 6.7
- Linux Kernel < 6.11
- Linux Kernel < 6.12.75
- Linux Kernel < 6.18.14
- Linux Kernel < 6.19.4
- Linux Kernel 6.11
Attack profile CVSS 3.1 · 7.5
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-45859.md and follow it. Check whether this project is affected by CVE-2026-45859. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://git.kernel.org/stable/c/207b3ebacb6113acaaec0d171d5307032c690004
- https://git.kernel.org/stable/c/23901aa6b8a2f294c4b774436b4691f3ff863a8f
- https://git.kernel.org/stable/c/79b713ef4261a8ead96af4703f89d0b5f25532e2
- https://git.kernel.org/stable/c/b740e7ddd7ca0dbfeafca3f5e52717206cf28524
References
- https://git.kernel.org/stable/c/207b3ebacb6113acaaec0d171d5307032c690004
- https://git.kernel.org/stable/c/23901aa6b8a2f294c4b774436b4691f3ff863a8f
- https://git.kernel.org/stable/c/4666688657e1054278b836b825fb88b2907e2da2
- https://git.kernel.org/stable/c/79b713ef4261a8ead96af4703f89d0b5f25532e2
- https://git.kernel.org/stable/c/aead84bdacd77e08357fd718e5dcaffaf387f3c3
- https://git.kernel.org/stable/c/b740e7ddd7ca0dbfeafca3f5e52717206cf28524