FKIE_CVE-2026-89555
Vulnerability from fkie_nvd - Published: 2026-09-11 20:19 - Updated: 2026-09-14 13:19
Severity
Summary
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.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/mpls/af_mpls.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "aa4fe0b450a461aa1162fe8375f5d28f4c957df8",
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"versionType": "git"
},
{
"lessThan": "b1c0783b2facc398437ad8f8b86c636d7a78f8db",
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"versionType": "git"
},
{
"lessThan": "bfaaff99238326166694354a63a76c02563f98b1",
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"versionType": "git"
},
{
"lessThan": "d9640239827d6d0cb84263b590f7a4f1596c17eb",
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"versionType": "git"
},
{
"lessThan": "fed638a248116b8a249bd4202d28e5934bdc65ad",
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"versionType": "git"
},
{
"lessThan": "d82b90a38c2ca8a0694428eab0e9551c23f2447d",
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"versionType": "git"
},
{
"lessThan": "49d38c1b4390412f8950d33dfaee0ccbd17beb81",
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"versionType": "git"
},
{
"lessThan": "29e63b8d9fc150cc191b1c6eb7e16e1247e1b650",
"status": "affected",
"version": "9f427a0e474a67b454420c131709600d44850486",
"versionType": "git"
},
{
"status": "affected",
"version": "ad864d9fce0ec56cc8f6afe5c6a0e6d7f484b9eb",
"versionType": "git"
},
{
"lessThan": "4.10",
"status": "affected",
"version": "4.9.8",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/mpls/af_mpls.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.10"
},
{
"lessThan": "4.10",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.270",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.221",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.188",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.109",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.50",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3-rc1",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmpls: reload header after pskb_may_pull()\n\nmpls_select_multipath() calls mpls_multipath_hash() to choose a nexthop\nwhen an MPLS route has multiple nexthops. While walking the MPLS label\nstack, the hash routine caches hdr for the current label. After finding\nthe bottom-of-stack label, it calls pskb_may_pull() before reading the\ninner IP header.\n\nIf an skb is constructed with the inner IP header in nonlinear data and\ninsufficient tailroom in the linear head, pskb_may_pull() calls\npskb_expand_head() to replace the skb head and free the old one. This\nleaves hdr pointing to freed memory. The IPv6 path can invalidate hdr\nagain when it performs a second pull for the larger header.\n\nThe issue was found through static analysis. A reproducer sending a legal\nGeneve packet through a bareudp/MPLS multipath setup triggered the same\nKASAN report in 2 of 2 unpatched runs:\n\n BUG: KASAN: slab-use-after-free in mpls_select_multipath\n Read of size 1 at addr ffff88800ecc6e20 by task ksoftirqd/1/23\n\n Call Trace:\n mpls_select_multipath\n mpls_forward\n __netif_receive_skb_list_core\n netif_receive_skb_list_internal\n napi_complete_done\n gro_cell_poll\n __napi_poll\n net_rx_action\n\n Freed by task 23:\n kfree\n pskb_expand_head\n __pskb_pull_tail\n mpls_select_multipath\n\nReload hdr from the current skb head after each successful pull before\nderiving the inner IPv4 or IPv6 header pointer."
}
],
"id": "CVE-2026-89555",
"lastModified": "2026-09-14T13:19:10.610",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-09-11T20:19:39.147",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/29e63b8d9fc150cc191b1c6eb7e16e1247e1b650"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/49d38c1b4390412f8950d33dfaee0ccbd17beb81"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/aa4fe0b450a461aa1162fe8375f5d28f4c957df8"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/b1c0783b2facc398437ad8f8b86c636d7a78f8db"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/bfaaff99238326166694354a63a76c02563f98b1"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/d82b90a38c2ca8a0694428eab0e9551c23f2447d"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/d9640239827d6d0cb84263b590f7a4f1596c17eb"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/fed638a248116b8a249bd4202d28e5934bdc65ad"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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