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VulnerabilityPublished Updated

CVE-2026-64535: Linux kernel · nvmet-tcp: Fix potential UAF when ddgst mismatch

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical · fixed in e091ff83d962f9ed00d9bd70443676de9fe98bdc : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 15:59 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 45% 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
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in e091ff83d962f9ed00d9bd70443676de9fe98bdc, dfb902462bca478f050224ec7a7195aafa7643b1, dbbd07d0a7020b80f6a7028e561908f7b83b3d5a +6
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Jul 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
  • >=5.10.20 <5.10.265
  • >=5.11.3 <5.12
Fixed in
  • e091ff83d962f9ed00d9bd70443676de9fe98bdc
  • dfb902462bca478f050224ec7a7195aafa7643b1
  • dbbd07d0a7020b80f6a7028e561908f7b83b3d5a
  • 96fe2513df590e74b04253a45089cae75569570e
  • 088ee46c18d99baef453afd74181dd40ade044ad
  • 7e558308eba14c8136cb1e615f0c850f76d1fc0a
  • 6f9442983a3e4227afd1c83a5251ddbca585ea21
  • 5.12
  • 5.10.265
LinuxLinuxAffected
  • =5.12
Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: Fix potential UAF when ddgst mismatch Shivam Kumar found via vulnerability testing: When data digest is enabled on an NVMe/TCP connection and a digest mismatch occurs on a non-final H2C_DATA PDU during an R2T-based data transfer, the digest error handler in nvmet_tcp_try_recv_ddgst() calls nvmet_req_uninit() — which performs percpu_ref_put() on the submission queue — but does NOT mark the command as completed. It does not set cqe->status, does not modify rbytes_done, and does not clear any flag. When the subsequent fatal error triggers queue teardown, nvmet_tcp_uninit_data_in_cmds() iterates all commands, checks nvmet_tcp_need_data_in() for each one, and finds that the already-uninited command still appears to need data (because rbytes_done < transfer_len and cqe->status == 0). It therefore calls nvmet_req_uninit() a second time on the same command — a double percpu_ref_put against a single percpu_ref_get.

References

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