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CVE-2026-74740· NVD / CVE Program· CNA Linux

net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain tcf_action_exec() handles TC_ACT_GOTO_CHAIN by first checking rcu_access_pointer(a->goto_chain) and then calling tcf_action_goto_chain_exec(), which does a second, independent rcu_dereference_bh(a->goto_chain) read and immediately dereferences chain->filter_chain. A concurrent tcf_action_set_ctrlact() (e.g. the gact replace path) can clear a->goto_chain between the two reads, so the second read returns NULL and tcf_action_goto_chain_exec() dereferences NULL. Fix the race by doing a single rcu_dereference_bh() read of a->goto_chain in tcf_action_exec(), checking it once for NULL, and passing the resulting chain pointer into tcf_action_goto_chain_exec(). This turns the split check/use into a single check/use on one value.

—No exploit Fix available
Published
Aug 26, 2026
Updated
Aug 26, 2026
EPSS
0.2% · 10th percentile
CWE
—
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Action score

0

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Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

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Affected systems

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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

    • 5.1affected
    • ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 and later · before 91d55fd1fdb85c8371ca8793c788ea7d5192383aaffected · git
    • ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 and later · before 1ec48b6715c29b20105e3485206602cff6c51ae5affected · git
    • ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 and later · before abceabc4408fca6a9dd52611f5d197dec9390d63affected · git
    • ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 and later · before 6b70886ebc428eed43a069c8944a931b5fb3f4e4affected · git
    • ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 and later · before f60b396ee174206fe08ebf997d16cd3801b77b22affected · git
    • before 5.1not affected · semver
    • 6.6.153 and later · up to and including 6.6.*not affected · semver
    • 6.12.105 and later · up to and including 6.12.*not affected · semver
    • 6.18.46 and later · up to and including 6.18.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxall versions—
Debian:12linux-6.12before 6.12.107-1~deb12u16.12.107-1~deb12u1
Debian:13linuxbefore 6.12.105-16.12.105-1
Debian:14linuxbefore 7.1.10-17.1.10-1

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
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  • CVE-2026-74309vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
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  • CVE-2026-74280crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
    40Plan
  • CVE-2026-74279crypto: cavium/cpt - fix DMA cleanup using wrong loop index
    40Plan

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 Linux1ec48b6715c29b20105e3485206602cff6c51ae5Vendor (CNA)
Linux Linux6b70886ebc428eed43a069c8944a931b5fb3f4e4Vendor (CNA)
Linux Linux91d55fd1fdb85c8371ca8793c788ea7d5192383aVendor (CNA)
Linux Linuxabceabc4408fca6a9dd52611f5d197dec9390d63Vendor (CNA)
Linux Linuxf60b396ee174206fe08ebf997d16cd3801b77b22Vendor (CNA)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.06.6.157.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.12.105-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.107-1~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.

No nightly-computed relations.

Chain candidates

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

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Bug bounty scope

No known public program.

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

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

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. Fix✗ → ✓

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References

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

All records