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NVD / CVE Program· CNA Linux

CVE-2026-74740: net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain

Noroxi assessment

Priority: Monitor (action score 0/100)

  • 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: 0.17% (FIRST EPSS).
  • Fixed version: Linux Linux 1ec48b6715c29b20105e3485206602cff6c51ae5, 6b70886ebc428eed43a069c8944a931b5fb3f4e4, 91d55fd1fdb85c8371ca8793c788ea7d5192383a; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 1ec48b6715c29b20105e3485206602cff6c51ae5, 6b70886ebc428eed43a069c8944a931b5fb3f4e4, 91d55fd1fdb85c8371ca8793c788ea7d5192383a; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1 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: 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
0.1% · 7th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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Noroxi analysis

What does it mean in your environment?

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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

    • 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:12linuxfrom 0—
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
    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-2026-74737Aug 26, 2026 · net: ethernet: ti: am65-cpsw-nuss: Fix port_id extraction from SRC TAG
    39Monitor
  • ← EarlierCVE-2026-74738Aug 26, 2026 · regmap: sdw-mbq: don't call an unset readable_reg callback
    0Monitor
  • Later →CVE-2026-74741Aug 26, 2026 · net: ngbe: fix NULL pointer dereference in non-MSI-X interrupt enabling
    30Monitor

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

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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.

—

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

Show all references (4 more)

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

All records