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NVD / CVE Program· CNA Linux

CVE-2026-89555: mpls: reload header after pskb_may_pull()

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: 0.69% (FIRST EPSS); higher than 52.9% of all records.
  • 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.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 29e63b8d9fc150cc191b1c6eb7e16e1247e1b650, 4.10, 49d38c1b4390412f8950d33dfaee0ccbd17beb81.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 29e63b8d9fc150cc191b1c6eb7e16e1247e1b650, 4.10, 49d38c1b4390412f8950d33dfaee0ccbd17beb81 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: 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.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Sep 11, 2026
Updated
Oct 19, 2026
EPSS
0.6% · 52th 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 · 0.6%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

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.

Get told when this record changes

  • 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
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  • 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

    • ad864d9fce0ec56cc8f6afe5c6a0e6d7f484b9eb, 4.10affected
    • 9f427a0e474a67b454420c131709600d44850486 and later · before aa4fe0b450a461aa1162fe8375f5d28f4c957df8affected · git
    • 9f427a0e474a67b454420c131709600d44850486 and later · before b1c0783b2facc398437ad8f8b86c636d7a78f8dbaffected · git
    • 9f427a0e474a67b454420c131709600d44850486 and later · before bfaaff99238326166694354a63a76c02563f98b1affected · git
    • 9f427a0e474a67b454420c131709600d44850486 and later · before d9640239827d6d0cb84263b590f7a4f1596c17ebaffected · git
    • 9f427a0e474a67b454420c131709600d44850486 and later · before fed638a248116b8a249bd4202d28e5934bdc65adaffected · git
    • 9f427a0e474a67b454420c131709600d44850486 and later · before d82b90a38c2ca8a0694428eab0e9551c23f2447daffected · git
    • 9f427a0e474a67b454420c131709600d44850486 and later · before 49d38c1b4390412f8950d33dfaee0ccbd17beb81affected · git
    • 9f427a0e474a67b454420c131709600d44850486 and later · before 29e63b8d9fc150cc191b1c6eb7e16e1247e1b650affected · git
    • 4.9.8 and later · before 4.10affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

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-2026-89553Sep 11, 2026 · nouveau/gem: reserve the bo in the info ioctl around the vma lookup
    31Monitor
  • ← EarlierCVE-2026-89554Sep 11, 2026 · mptcp: fix uninitialized local_id in syncookie MP_JOIN reconstruction
    32Monitor
  • Later →CVE-2026-89556Sep 11, 2026 · module: validate string table section types
    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 Linux29e63b8d9fc150cc191b1c6eb7e16e1247e1b650Vendor (CNA)
Linux Linux4.10Vendor (CNA)
Linux Linux49d38c1b4390412f8950d33dfaee0ccbd17beb81Vendor (CNA)
Linux Linuxaa4fe0b450a461aa1162fe8375f5d28f4c957df8Vendor (CNA)
Linux Linuxb1c0783b2facc398437ad8f8b86c636d7a78f8dbVendor (CNA)
Linux Linuxbfaaff99238326166694354a63a76c02563f98b1Vendor (CNA)
Linux Linuxd82b90a38c2ca8a0694428eab0e9551c23f2447dVendor (CNA)
Linux Linuxd9640239827d6d0cb84263b590f7a4f1596c17ebVendor (CNA)
Linux Linuxfed638a248116b8a249bd4202d28e5934bdc65adVendor (CNA)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~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. SSVC exploitation— → none
  2. 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