mpls: reload header after pskb_may_pull()
In 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.
CVE-2026-89555
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-89555
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"lessThan": "aa4fe0b450a461aa1162fe8375f5d28f4c957df8",
"versionType": "git"
},
{
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"lessThan": "b1c0783b2facc398437ad8f8b86c636d7a78f8db",
"versionType": "git"
},
{
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"lessThan": "bfaaff99238326166694354a63a76c02563f98b1",
"versionType": "git"
},
{
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"lessThan": "d9640239827d6d0cb84263b590f7a4f1596c17eb",
"versionType": "git"
},
{
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"lessThan": "fed638a248116b8a249bd4202d28e5934bdc65ad",
"versionType": "git"
},
{
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"lessThan": "d82b90a38c2ca8a0694428eab0e9551c23f2447d",
"versionType": "git"
},
{
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"lessThan": "49d38c1b4390412f8950d33dfaee0ccbd17beb81",
"versionType": "git"
},
{
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"lessThan": "29e63b8d9fc150cc191b1c6eb7e16e1247e1b650",
"versionType": "git"
},
{
"status": "affected",
"version": "ad864d9fce0ec56cc8f6afe5c6a0e6d7f484b9eb",
"versionType": "git"
},
{
"status": "affected",
"version": "4.9.8",
"lessThan": "4.10",
"versionType": "semver"
}
],
"programFiles": [
"net/mpls/af_mpls.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.10"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.10",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.270",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.221",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.188",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.109",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.50",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/mpls/af_mpls.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-89555
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #35070 · Revision 1
- Added to Heist Feed
- Publisher date