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NVD / CVE Program· CNA Linux

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

Noroxi assessment

Priority: Monitor (action score 39/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.54% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 088ee46c18d99baef453afd74181dd40ade044ad, 5.10.265, 5.12; azl3 kernel 6.6.145.2-1 on Azure Linux 3.0 6.6.150.1-1.

Low priority for now. Upgrade to Linux Linux 088ee46c18d99baef453afd74181dd40ade044ad, 5.10.265, 5.12; azl3 kernel 6.6.145.2-1 on Azure Linux 3.0 6.6.150.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Jul 27, 2026
Updated
Oct 19, 2026
EPSS
0.5% · 45th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 4b17476d809273617d3317fa0d4ae78aa488d760, 5.12affected
    • 91edfca6f8b364d60cde3ddefaf7d03ddf35774b and later · before dfb902462bca478f050224ec7a7195aafa7643b1affected · git
    • fda871c0ba5d2eed2cd1c881573168129da70058 and later · before 7e558308eba14c8136cb1e615f0c850f76d1fc0aaffected · git
    • fda871c0ba5d2eed2cd1c881573168129da70058 and later · before 96fe2513df590e74b04253a45089cae75569570eaffected · git
    • fda871c0ba5d2eed2cd1c881573168129da70058 and later · before e091ff83d962f9ed00d9bd70443676de9fe98bdcaffected · git
    • fda871c0ba5d2eed2cd1c881573168129da70058 and later · before 6f9442983a3e4227afd1c83a5251ddbca585ea21affected · git
    • fda871c0ba5d2eed2cd1c881573168129da70058 and later · before 088ee46c18d99baef453afd74181dd40ade044adaffected · git
    • fda871c0ba5d2eed2cd1c881573168129da70058 and later · before dbbd07d0a7020b80f6a7028e561908f7b83b3d5aaffected · git
    • 5.10.20 and later · before 5.10.265affected · semver
    • 5.11.3 and later · before 5.12affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.180-16.1.180-1
Debian:12linux-6.12before 6.12.100-1~deb12u16.12.100-1~deb12u1
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.3-17.1.3-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-64533Jul 27, 2026 · fs/ntfs3: validate lcns_follow in log_replay conversion
    31Monitor
  • ← EarlierCVE-2026-64534Jul 27, 2026 · nvmet-tcp: check INIT_FAILED before nvmet_req_uninit in digest error path
    39Monitor
  • Later →CVE-2026-64536Jul 27, 2026 · staging: rtl8723bs: fix OOB reads in is_ap_in_tkip() IE loop
    32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux088ee46c18d99baef453afd74181dd40ade044adVendor (CNA)
Linux Linux5.10.265Vendor (CNA)
Linux Linux5.12Vendor (CNA)
Linux Linux6f9442983a3e4227afd1c83a5251ddbca585ea21Vendor (CNA)
Linux Linux7e558308eba14c8136cb1e615f0c850f76d1fc0aVendor (CNA)
Linux Linux96fe2513df590e74b04253a45089cae75569570eVendor (CNA)
Linux Linuxdbbd07d0a7020b80f6a7028e561908f7b83b3d5aVendor (CNA)
Linux Linuxdfb902462bca478f050224ec7a7195aafa7643b1Vendor (CNA)
Linux Linuxe091ff83d962f9ed00d9bd70443676de9fe98bdcVendor (CNA)
azl3 kernel 6.6.145.2-1 on Azure Linux 3.06.6.150.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.180-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.100-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-6459710 days apartsmb: client: fix double-free in SMB2_close() replay
    39Monitor
  • CVE-2026-6819214 days apartwifi: brcmfmac: make release_scratchbuffers idempotent
    35Monitor
  • CVE-2026-645709 days apartwifi: mac80211: fix fils_discovery double free on alloc failure
    31Monitor
  • CVE-2026-645809 days apartxfrm6: clear dst.dev on error to avoid double netdev_put in xfrm6_fill_dst()
    31Monitor
  • CVE-2026-6459910 days apartcrypto: amlogic - avoid double cleanup in meson_crypto_probe()
    31Monitor
  • CVE-2026-6823614 days apartdrm/amd/display: set new_stream to NULL after release
    31Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-415 · Double Free

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records