mpls: reload header after pskb_may_pull()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89555
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:39 UTC
Updated2026-09-14 13:19:10 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: mpls: reload header after pskb_may_pull() mpls_select_multipath() calls mpls_multipath_hash() to choose a nexthop when an MPLS route has multiple nexthops. While walking the MPLS label stack, the hash routine caches hdr for the current label. After finding the bottom-of-stack label, it calls pskb_may_pull() before reading the inner IP header. If an skb is constructed with the inner IP header in nonlinear data and insufficient tailroom in the linear head, pskb_may_pull() calls pskb_expand_head() to replace the skb head and free the old one. This leaves hdr pointing to freed memory. The IPv6 path can invalidate hdr again when it performs a second pull for the larger header. The issue was found through static analysis. A reproducer sending a legal Geneve packet through a bareudp/MPLS multipath setup triggered the same KASAN report in 2 of 2 unpatched runs: BUG: KASAN: slab-use-after-free in mpls_select_multipath Read of size 1 at addr ffff88800ecc6e20 by task ksoftirqd/1/23 Call Trace: mpls_select_multipath mpls_forward __netif_receive_skb_list_core netif_receive_skb_list_internal napi_complete_done gro_cell_poll __napi_poll net_rx_action Freed by task 23: kfree pskb_expand_head __pskb_pull_tail mpls_select_multipath Reload hdr from the current skb head after each successful pull before deriving the inner IPv4 or IPv6 header pointer.

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: 0.006080000 probability, percentile 0.472480000 (date 2026-09-14)

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 9f427a0e474a67b454420c131709600d44850486 aa4fe0b450a461aa1162fe8375f5d28f4c957df8 git Not specified
CNA Linux Linux affected 9f427a0e474a67b454420c131709600d44850486 b1c0783b2facc398437ad8f8b86c636d7a78f8db git Not specified
CNA Linux Linux affected 9f427a0e474a67b454420c131709600d44850486 bfaaff99238326166694354a63a76c02563f98b1 git Not specified
CNA Linux Linux affected 9f427a0e474a67b454420c131709600d44850486 d9640239827d6d0cb84263b590f7a4f1596c17eb git Not specified
CNA Linux Linux affected 9f427a0e474a67b454420c131709600d44850486 fed638a248116b8a249bd4202d28e5934bdc65ad git Not specified
CNA Linux Linux affected 9f427a0e474a67b454420c131709600d44850486 d82b90a38c2ca8a0694428eab0e9551c23f2447d git Not specified
CNA Linux Linux affected 9f427a0e474a67b454420c131709600d44850486 49d38c1b4390412f8950d33dfaee0ccbd17beb81 git Not specified
CNA Linux Linux affected 9f427a0e474a67b454420c131709600d44850486 29e63b8d9fc150cc191b1c6eb7e16e1247e1b650 git Not specified
CNA Linux Linux affected ad864d9fce0ec56cc8f6afe5c6a0e6d7f484b9eb git Not specified
CNA Linux Linux affected 4.9.8 4.10 semver Not specified
CNA Linux Linux affected 4.10 Not specified
CNA Linux Linux unaffected 4.10 semver Not specified
CNA Linux Linux unaffected 5.10.270 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.221 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.188 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.157 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/d82b90a38c2ca8a0694428eab0e9551c23f2447d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/49d38c1b4390412f8950d33dfaee0ccbd17beb81 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/aa4fe0b450a461aa1162fe8375f5d28f4c957df8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fed638a248116b8a249bd4202d28e5934bdc65ad 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bfaaff99238326166694354a63a76c02563f98b1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/29e63b8d9fc150cc191b1c6eb7e16e1247e1b650 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d9640239827d6d0cb84263b590f7a4f1596c17eb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b1c0783b2facc398437ad8f8b86c636d7a78f8db 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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