CVE Intelligence
Critical Memory corruption

CVE-2026-43501 — ipv6: rpl: reserve mac_len headroom when recompressed SRH grows

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.

Published May 21, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Linux

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 1% (30-day exploitation probability)+9
  • Technical severity (critical)+10

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.99%
ahead of 62% of scored CVEs · Oct 14, 2026
Affects
Linux
Linux and 1 more
CVSS base
9.8
Critical · 3 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. Apply the fixed version or the patch documented under Remediation.
  4. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Linux Linux ≥ 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and < bde199c72d319a4e207f88daabc888317504e2fbversion 5.7≥ 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and < 9e6bf146b55999a095bb14f73a843942456d1adc≥ 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and < 7398ebefbfd4f8a31d4f665a4213302fa995494b≥ 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and < c261d07a80576dc8ccf394ef8f074f8c67a06b37≥ 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and < 4babc2d9fda2df43823b85d08a0180b68f1b0854≥ 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and < 8e8be63465a5e80394c70324603dfea1bfdad48f≥ 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and < 0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402
and 1 more ≥ 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 and < be1fa0aa9b4fdd5a8b7a61ba520a690a68391e6e
Vulnerable CVE Program (cve.org) e CISA ADP
Linux Linux Kernel ≥ 5.7 and < 5.10.258version 7.1-rc1≥ 6.19 and < 7.0.4≥ 6.13 and < 6.18.27≥ 6.7 and < 6.12.86≥ 6.2 and < 6.6.140≥ 5.16 and < 6.1.175≥ 5.11 and < 5.15.209 Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
9.8 CVSS 3.1 Critical 3.9 5.9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database
9.8 CVSS 3.1 Critical — — Linux via CVE Program (cve.org) e CISA ADP
7.5 CVSS 3.1 High 1.6 5.9 0b0ca135-0b70-47e7-9f44-1890c2a1c46c via NIST National Vulnerability Database
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67)
Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 9.8 (416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-787 · Out-of-bounds Write

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.99%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · linux/linux
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • Fix documented
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVSS changed · 9.8
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVE published
    May 21, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 15, 2026 – Oct 15, 2026
  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

20 on the record

Elsewhere on this site

Linux
every CVE for this vendor
Memory corruption
same class
CWE-787
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-99999 ipv4: validate checksum_start before completing checksum 8h
  • CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 8h
  • CVE-2026-98428 ALSA: usb: 6fire: Avoid embedded URBs 1d
  • CVE-2026-98431 RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency 1d
  • CVE-2026-98430 RDMA/efa: Keep admin queues alive while IRQ is registered 1d
  • CVE-2026-98429 RDMA/efa: Keep EQ resources alive while IRQ is registered 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No CISA SSVC assessment.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-43501 is "ipv6: rpl: reserve mac_len headroom when recompressed SRH grows", rated Critical. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 0.99% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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