DEBIAN-CVE-2026-23016

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Source
https://security-tracker.debian.org/tracker/CVE-2026-23016
Import Source
https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-23016.json
JSON Data
https://api.osv.dev/v1/vulns/DEBIAN-CVE-2026-23016
Upstream
Published
2026-01-31T12:16:04Z
Modified
2026-09-14T17:02:48Z
Severity
  • 5.5 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
[none]
Details

In the Linux kernel, the following vulnerability has been resolved: inet: frags: drop fraglist conntrack references Jakub added a warning in nf_conntrack_cleanup_net_list() to make debugging leaked skbs/conntrack references more obvious. syzbot reports this as triggering, and I can also reproduce this via ip_defrag.sh selftest: conntrack cleanup blocked for 60s WARNING: net/netfilter/nf_conntrack_core.c:2512 [..] conntrack clenups gets stuck because there are skbs with still hold nf_conn references via their frag_list. net.core.skb_defer_max=0 makes the hang disappear. Eric Dumazet points out that skb_release_head_state() doesn't follow the fraglist. ip_defrag.sh can only reproduce this problem since commit 6471658dc66c ("udp: use skb_attempt_defer_free()"), but AFAICS this problem could happen with TCP as well if pmtu discovery is off. The relevant problem path for udp is: 1. netns emits fragmented packets 2. nf_defrag_v6_hook reassembles them (in output hook) 3. reassembled skb is tracked (skb owns nf_conn reference) 4. ip6_output refragments 5. refragmented packets also own nf_conn reference (ip6_fragment calls ip6_copy_metadata()) 6. on input path, nf_defrag_v6_hook skips defragmentation: the fragments already have skb->nf_conn attached 7. skbs are reassembled via ipv6_frag_rcv() 8. skb_consume_udp -> skb_attempt_defer_free() -> skb ends up in pcpu freelist, but still has nf_conn reference. Possible solutions: 1 let defrag engine drop nf_conn entry, OR 2 export kick_defer_list_purge() and call it from the conntrack netns exit callback, OR 3 add skb_has_frag_list() check to skb_attempt_defer_free() 2 & 3 also solve ip_defrag.sh hang but share same drawback: Such reassembled skbs, queued to socket, can prevent conntrack module removal until userspace has consumed the packet. While both tcp and udp stack do call nf_reset_ct() before placing skb on socket queue, that function doesn't iterate frag_list skbs. Therefore drop nf_conn entries when they are placed in defrag queue. Keep the nf_conn entry of the first (offset 0) skb so that reassembled skb retains nf_conn entry for sake of TX path. Note that fixes tag is incorrect; it points to the commit introducing the 'ip_defrag.sh reproducible problem': no need to backport this patch to every stable kernel.

References

Affected packages

Debian:14 / linux

Package

Name
linux
Purl
pkg:deb/debian/linux?arch=source&distro=forky

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
6.18.8-1

Affected versions

6.*
6.12.38-1
6.12.41-1
6.12.43-1~bpo12+1
6.12.43-1
6.12.48-1
6.12.57-1~bpo12+1
6.12.57-1
6.12.63-1~bpo12+1
6.12.63-1
6.12.69-1~bpo12+1
6.12.69-1
6.12.73-1~bpo12+1
6.12.73-1
6.12.74-1
6.12.74-2~bpo12+1
6.12.74-2
6.12.85-1~bpo12+1
6.12.85-1
6.12.86-1~bpo12+1
6.12.86-1
6.12.88-1~bpo12+1
6.12.88-1
6.12.90-1~bpo12+1
6.12.90-1
6.12.90-2~bpo12+1
6.12.90-2
6.12.94-1~bpo12+1
6.12.94-1
6.12.95-1~bpo12+1
6.12.95-1
6.12.96-1
6.12.100-1
6.12.101-1
6.12.105-1
6.12.107-1
6.13~rc6-1~exp1
6.13~rc7-1~exp1
6.13.2-1~exp1
6.13.3-1~exp1
6.13.4-1~exp1
6.13.5-1~exp1
6.13.6-1~exp1
6.13.7-1~exp1
6.13.8-1~exp1
6.13.9-1~exp1
6.13.10-1~exp1
6.13.11-1~exp1
6.14.3-1~exp1
6.14.5-1~exp1
6.14.6-1~exp1
6.15~rc7-1~exp1
6.15-1~exp1
6.15.1-1~exp1
6.15.2-1~exp1
6.15.3-1~exp1
6.15.4-1~exp1
6.15.5-1~exp1
6.15.6-1~exp1
6.16~rc7-1~exp1
6.16-1~exp1
6.16.1-1~exp1
6.16.3-1~bpo13+1
6.16.3-1
6.16.5-1
6.16.6-1
6.16.7-1
6.16.8-1
6.16.9-1
6.16.10-1
6.16.11-1
6.16.12-1~bpo13+1
6.16.12-1
6.16.12-2
6.17.2-1~exp1
6.17.5-1~exp1
6.17.6-1
6.17.7-1
6.17.7-2
6.17.8-1~bpo13+1
6.17.8-1
6.17.9-1
6.17.10-1
6.17.11-1
6.17.12-1
6.17.13-1~bpo13+1
6.17.13-1
6.18~rc4-1~exp1
6.18~rc4-1~exp2
6.18~rc5-1~exp1
6.18~rc6-1~exp1
6.18~rc7-1~exp1
6.18.1-1~exp1
6.18.2-1~exp1
6.18.3-1
6.18.5-1~bpo13+1
6.18.5-1

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-23016.json"