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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74478
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 13:17:52 UTC
Updated2026-08-17 06:19:43 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.002010000 probability, percentile 0.103740000 (date 2026-08-16)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb 4b9601595e8b6b5d18878cac0aeabc687d241111 git Not specified
CNA Linux Linux affected 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb 67d58ab4f2ccf7145f3da07e025735a09c79de1b git Not specified
CNA Linux Linux affected 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb 180ff4c81faf01ec4e06082c9daa7c40518ead89 git Not specified
CNA Linux Linux affected 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb 804b681002ead233abf49a3efd681f5468a835f9 git Not specified
CNA Linux Linux affected 49da7e64f33e80edffb1a9eeb230fa4c3f42dffb af421e9aed3920c7ac88c24daa48606c7112feca git Not specified
CNA Linux Linux affected 4.17 Not specified
CNA Linux Linux unaffected 4.17 semver Not specified
CNA Linux Linux unaffected 6.6.151 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.103 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.44 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.8 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/af421e9aed3920c7ac88c24daa48606c7112feca 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/804b681002ead233abf49a3efd681f5468a835f9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/180ff4c81faf01ec4e06082c9daa7c40518ead89 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/67d58ab4f2ccf7145f3da07e025735a09c79de1b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4b9601595e8b6b5d18878cac0aeabc687d241111 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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