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Fencer Vulns
high 8.2

CVE-2026-72057 json

net/sched: act_ct: preserve tc_skb_cb across defragmentation

published 2026-08-15 2 mo ago modified 2026-10-19 20 d ago also EUVD-2026-59015

cvss
8.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

net/sched: act_ct: preserve tc_skb_cb across defragmentation

tcf_ct_handle_fragments() calls nf_ct_handle_fragments() without saving and restoring skb->cb. The defrag helper clears IPCB/IP6CB, which aliases the tc_skb_cb/qdisc_skb_cb control buffer. Fragmented traffic through act_ct therefore loses qdisc metadata such as pkt_segs and can trigger WARN_ON_ONCE() in qdisc_pkt_segs() when panic_on_warn is enabled.

Save and restore the full tc_skb_cb around nf_ct_handle_fragments(), matching the pattern used by ovs_ct_handle_fragments().

Patch / fix

  • Linux Linux 5.15.217, 6.1.184, 6.6.145, 6.12.97, 6.18.40, 7.1.5, 7.2
  • linux Debian 12 6.1.187-1
  • linux Debian 13 6.12.100-1
  • linux Debian 14 7.1.5-1

debian advisories DEBIAN-CVE-2026-72057

  • linux Ubuntu 22.04 LTS 5.15.0-202.212
  • linux Ubuntu 24.04 LTS 6.8.0-147.147
  • linux Ubuntu 26.04 LTS 7.0.0-38.38
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1119.126
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1067.70
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1014.14
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1120.130
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1071.79

ubuntu advisories UBUNTU-CVE-2026-72057

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-72057 updated cvss 5.3

kernel: net/sched: act_ct: preserve tc_skb_cb across defragmentation

  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
23 d ago

Exploit prediction

0.58% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.