CVE-2026-45859
published 2026-05-27CVE-2026-45859: In the Linux kernel, the following vulnerability has been resolved: netfilter: nfnetlink_queue: do shared-unconfirmed check before segmentation Ulrich reports…
high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
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.
Affected
14 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| linux | linux | — | — |
| linux | linux | — | — |
| linux | linux | — | — |
| linux | linux | — | — |
| linux | linux | — | — |
| linux | linux | >= 5.15.166 < 5.16 | 5.16 |
| linux | linux | >= 6.1.107 < 6.2 | 6.2 |
| linux | linux | >= 6.10.7 < 6.11 | 6.11 |
| linux | linux | >= 6.6.48 < 6.7 | 6.7 |
| linux | linux | >= 7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb < 79b713ef4261a8ead96af4703f89d0b5f25532e2 | 79b713ef4261a8ead96af4703f89d0b5f25532e2 |
| linux | linux | >= 7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb < 23901aa6b8a2f294c4b774436b4691f3ff863a8f | 23901aa6b8a2f294c4b774436b4691f3ff863a8f |
| linux | linux | >= 7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb < b740e7ddd7ca0dbfeafca3f5e52717206cf28524 | b740e7ddd7ca0dbfeafca3f5e52717206cf28524 |
| linux | linux | >= 7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb < 207b3ebacb6113acaaec0d171d5307032c690004 | 207b3ebacb6113acaaec0d171d5307032c690004 |
| linux | linux_kernel | — | — |