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NVD / CVE Program· CNA Linux

CVE-2026-74478: um: vector: fix use-after-free in vector_mmsg_rx()

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: 0.57% (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.
  • Fixed version: Linux Linux 180ff4c81faf01ec4e06082c9daa7c40518ead89, 4b9601595e8b6b5d18878cac0aeabc687d241111, 67d58ab4f2ccf7145f3da07e025735a09c79de1b.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 180ff4c81faf01ec4e06082c9daa7c40518ead89, 4b9601595e8b6b5d18878cac0aeabc687d241111, 67d58ab4f2ccf7145f3da07e025735a09c79de1b 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: um: vector: fix use-after-free in vector_mmsg_rx() When vector_mmsg_rx() discards a packet whose overlay header fails verify_header(), it frees the skb and continues the loop: if (header_check < 0) { dev_kfree_skb_irq(skb); vp->estats.rx_encaps_errors++; continue; } The normal and short-packet paths fall through to the bottom of the loop body, which clears the consumed slot and advances the cursors: (*skbuff_vector) = NULL; mmsg_vector++; skbuff_vector++; The verify_header() < 0 path skips that via continue, so the freed skb is left in skbuff_vector[] and the cursors do not advance. The next iteration reads the same slot, gets the freed skb, and frees it again, producing a refcount underflow / use-after-free in the RX path. Discard the slot the same way the other paths do before continuing. Only transports whose verify_header() can return negative are affected: GRE and L2TPv3 do so on a cookie/session-id mismatch (raw/tap do not), so any peer on such a transport can trigger it without authentication.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Aug 15, 2026
Updated
Aug 19, 2026
EPSS
0.5% · 47th percentile
CWE
—

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%

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

    • 4.17affected
    • 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and later · before 967c779c9853d2a1cc9cd8e61d300250c348f3d9affected · git
    • 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and later · before a7bc015bb798c525e7a82dd14225c6aeb994274baffected · git
    • 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and later · before 7dc9781e320d664c9bdd50003c9acfddf363d1e1affected · git
    • 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and later · before 4b9601595e8b6b5d18878cac0aeabc687d241111affected · git
    • 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and later · before 67d58ab4f2ccf7145f3da07e025735a09c79de1baffected · git
    • 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and later · before 180ff4c81faf01ec4e06082c9daa7c40518ead89affected · git
    • 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and later · before 804b681002ead233abf49a3efd681f5468a835f9affected · git
    • 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb and later · before af421e9aed3920c7ac88c24daa48606c7112fecaaffected · git
    • before 4.17not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.187-16.1.187-1
Debian:12linux-6.12before 6.12.107-1~deb12u16.12.107-1~deb12u1
Debian:13linuxbefore 6.12.105-16.12.105-1
Debian:14linuxbefore 7.1.8-17.1.8-1

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-2026-74472Aug 15, 2026 · ublk: reset kernel-owned dev_info fields in ublk_ctrl_add_dev()
    0Monitor
  • ← EarlierCVE-2026-74477Aug 15, 2026 · uprobes: Fix NULL pointer dereference in hprobe_expire()
    0Monitor
  • Later →CVE-2026-74483Aug 15, 2026 · binfmt_misc: don't leak the user namespace when the mount fails
    0Monitor

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 Linux180ff4c81faf01ec4e06082c9daa7c40518ead89Vendor (CNA)
Linux Linux4b9601595e8b6b5d18878cac0aeabc687d241111Vendor (CNA)
Linux Linux67d58ab4f2ccf7145f3da07e025735a09c79de1bVendor (CNA)
Linux Linux7dc9781e320d664c9bdd50003c9acfddf363d1e1Vendor (CNA)
Linux Linux804b681002ead233abf49a3efd681f5468a835f9Vendor (CNA)
Linux Linux967c779c9853d2a1cc9cd8e61d300250c348f3d9Vendor (CNA)
Linux Linuxa7bc015bb798c525e7a82dd14225c6aeb994274bVendor (CNA)
Linux Linuxaf421e9aed3920c7ac88c24daa48606c7112fecaVendor (CNA)
debian:linux6.1.187-1 · Debian:12Package 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.

—

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

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)

—

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. Fix✗ → ✓

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

References

Show all references (7 more)

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

All records