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VulnerabilityPublished Updated

CVE-2026-72057: Linux kernel · net/sched: act_ct: preserve tc_skb_cb across defragmentation

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 8.2 High · fixed in fb080b6f54835d5d4d11ce3122800e6f0f6689e6 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:30 UTC

CVSS 3.1 base score
8.2High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 47% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers can reliably automate steps 1–4 of the kill chain
Technical impact
Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in fb080b6f54835d5d4d11ce3122800e6f0f6689e6, f7f45ceb855d9ba1cba594fb3f383255f7013fad, b3d835407846134b0d54637c0281b39bebef831d +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • >=5.15.13 <5.15.217
Fixed in
  • fb080b6f54835d5d4d11ce3122800e6f0f6689e6
  • f7f45ceb855d9ba1cba594fb3f383255f7013fad
  • b3d835407846134b0d54637c0281b39bebef831d
  • 9092e15defbe6c7bc241c306093ca9d358a578e7
  • 2400c4b05d58834b994500a9eec90a37db44187c
  • 67d6b00a54446c008f52cf70fc0c2ad0c712f85d
  • 5c3ae5f6c7c6de73ea9b6a75154fe4ed343e1bac
  • 5.15.217
LinuxLinuxAffected
  • =5.16
Fixed in–

Description

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().

References

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