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CVE-2026-43501· NVD / CVE Program· CNA Linux

ipv6: rpl: reserve mac_len headroom when recompressed SRH grows

Noroxi assessment

Priority: Monitor (action score 39/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.99% (FIRST EPSS); higher than 62.1% 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 0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402, 4babc2d9fda2df43823b85d08a0180b68f1b0854, 7398ebefbfd4f8a31d4f665a4213302fa995494b; azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 6.6.141.1-1.

Low priority for now. Upgrade to Linux Linux 0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402, 4babc2d9fda2df43823b85d08a0180b68f1b0854, 7398ebefbfd4f8a31d4f665a4213302fa995494b; azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 6.6.141.1-1 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: ipv6: rpl: reserve mac_len headroom when recompressed SRH grows ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->daddr, recompresses, then pulls the old header and pushes the new one plus the IPv6 header back. The recompressed header can be larger than the received one when the swap reduces the common-prefix length the segments share with daddr (CmprI=0, CmprE>0, seg[0][0] != daddr[0] gives the maximum +8 bytes). pskb_expand_head() was gated on segments_left == 0, so on earlier segments the push consumed unchecked headroom. Once skb_push() leaves fewer than skb->mac_len bytes in front of data, skb_mac_header_rebuild()'s call to: skb_set_mac_header(skb, -skb->mac_len); will store (data - head) - mac_len into the u16 mac_header field, which wraps to ~65530, and the following memmove() writes mac_len bytes ~64KiB past skb->head. A single AF_INET6/SOCK_RAW/IPV6_HDRINCL packet over lo with a two segment type-3 SRH (CmprI=0, CmprE=15) reaches headroom 8 after one pass; KASAN reports a 14-byte OOB write in ipv6_rthdr_rcv. Fix this by expanding the head whenever the remaining room is less than the push size plus mac_len, and request that much extra so the rebuilt MAC header fits afterwards.

CriticalCVSS 9.8 · v3.1—Proof of concept Fix available
Published
May 21, 2026
Updated
Oct 19, 2026
EPSS
0.9% · 62th percentile

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 · 0.9%

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.

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  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

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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.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.7 and later · before 5.10.258
  • linux linux kernel5.11 and later · before 5.15.209
  • linux linux kernel5.16 and later · before 6.1.175
  • linux linux kernel6.2 and later · before 6.6.140
  • linux linux kernel6.7 and later · before 6.12.86
  • linux linux kernel6.13 and later · before 6.18.27
  • linux linux kernel6.19 and later · before 7.0.4
  • linux linux kernel7.1

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

    • 5.7affected
    • 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and later · before bde199c72d319a4e207f88daabc888317504e2fbaffected · git
    • 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and later · before be1fa0aa9b4fdd5a8b7a61ba520a690a68391e6eaffected · git
    • 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and later · before 0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402affected · git
    • 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and later · before 8e8be63465a5e80394c70324603dfea1bfdad48faffected · git
    • 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and later · before 4babc2d9fda2df43823b85d08a0180b68f1b0854affected · git
    • 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and later · before c261d07a80576dc8ccf394ef8f074f8c67a06b37affected · git
    • 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and later · before 7398ebefbfd4f8a31d4f665a4213302fa995494baffected · git
    • 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and later · before 9e6bf146b55999a095bb14f73a843942456d1adcaffected · git
    • before 5.7not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.22.1.el10_26.12.0-211.22.1.el10_2

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now
  • CVE-2016-5195Race condition in mm/gup.c in the Linux kernel 2.x through 4.x before 4.8.3 allows local users to gain privileges by leveraging incorrect haKEV
    83Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-43496May 21, 2026 · net/sched: sch_red: Replace direct dequeue call with peek and qdisc_dequeue_peeked
    22Monitor
  • ← EarlierCVE-2026-43499May 21, 2026 · rtmutex: Use waiter::task instead of current in remove_waiter()
    31Monitor
  • Later →CVE-2026-43502May 21, 2026 · net/rds: handle zerocopy send cleanup before the message is queued
    31Monitor

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 Linux0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402Vendor (CNA)
Linux Linux4babc2d9fda2df43823b85d08a0180b68f1b0854Vendor (CNA)
Linux Linux7398ebefbfd4f8a31d4f665a4213302fa995494bVendor (CNA)
Linux Linux8e8be63465a5e80394c70324603dfea1bfdad48fVendor (CNA)
Linux Linux9e6bf146b55999a095bb14f73a843942456d1adcVendor (CNA)
Linux Linuxbde199c72d319a4e207f88daabc888317504e2fbVendor (CNA)
Linux Linuxbe1fa0aa9b4fdd5a8b7a61ba520a690a68391e6eVendor (CNA)
Linux Linuxc261d07a80576dc8ccf394ef8f074f8c67a06b37Vendor (CNA)
azl3 kernel 6.6.139.1-1 on Azure Linux 3.06.6.141.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:kernel6.12.0-211.22.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k6.12.0-211.22.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-core6.12.0-211.22.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug6.12.0-211.22.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-core6.12.0-211.22.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel6.12.0-211.22.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched6.12.0-211.22.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules6.12.0-211.22.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-core6.12.0-211.22.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra6.12.0-211.22.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel6.12.0-211.22.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel-matched6.12.0-211.22.1.el10_2 · AlmaLinux:10Package registry (OSV)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)
opensuse:kernel-source7.0.10-1.1 · openSUSE:TumbleweedPackage registry (OSV)
red hat:kernel-64k-debug-debuginfo0:6.12.0-211.22.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel0:6.12.0-211.22.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel-matched0:6.12.0-211.22.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debuginfo0:6.12.0-211.22.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel0:6.12.0-211.22.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel-matched0:6.12.0-211.22.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-debuginfo0:6.12.0-211.22.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)

+18

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×2

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02026-06-19
Proof-of-concept repository on GitHubstars:72026-07-11

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.

  1. Published
  2. First PoC+28 d
  3. TodayOct 24, 2026+156 d
EPSS, last 120 days+1% in 7 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).

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)

CWE-787 · Out-of-bounds Write

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 (19 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records