CVE-2026-43501: Linux kernel · ipv6: rpl: reserve mac_len headroom when recompressed SRH grows
Source GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in c261d07a80576dc8ccf394ef8f074f8c67a06b37 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in c261d07a80576dc8ccf394ef8f074f8c67a06b37, be1fa0aa9b4fdd5a8b7a61ba520a690a68391e6e, bde199c72d319a4e207f88daabc888317504e2fb +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 21 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
AI-suggested
A fix is available from Red Hat as a kernel update for Red Hat Enterprise Linux 9 and 10 and Red Hat In-Vehicle OS 2. Systems should apply the updated kernel packages and reboot to remediate the vulnerability. As a temporary mitigation, administrators can disable IPv6 Source Routing by setting the sysctl parameters net.ipv6.conf.all.accept_source_route=0 and net.ipv6.conf.default.accept_source_route=0. This prevents the kernel from processing IPv6 Source Routing Headers and avoids the vulnerable code path. Note that disabling IPv6 Source Routing may impact network configurations relying on this feature.
Description
A critical vulnerability (CVE-2026-43501) in the Linux kernel's IPv6 Source Routing Header (SRH) recompression process allows a local attacker to trigger an out-of-bounds write due to insufficient reserved headroom. This memory corruption can lead to denial of service or potentially arbitrary code execution. The flaw affects Red Hat Enterprise Linux 9 and 10, and Red Hat In-Vehicle OS 2. A patch is available from Red Hat, and a mitigation involves disabling IPv6 Source Routing by setting the accept_source_route sysctl parameter to 0. Systems should apply the vendor-provided kernel update and reboot to remediate the issue.
References
- nvd.nist.gov/vuln/detail/CVE-2026-43501 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43501.json (opens in a new tab)
- git.kernel.org/stable/c/c261d07a80576dc8ccf394ef8f074f8c67a06b37 (opens in a new tab)
- git.kernel.org/stable/c/be1fa0aa9b4fdd5a8b7a61ba520a690a68391e6e (opens in a new tab)
- git.kernel.org/stable/c/bde199c72d319a4e207f88daabc888317504e2fb (opens in a new tab)
- git.kernel.org/stable/c/9e6bf146b55999a095bb14f73a843942456d1adc (opens in a new tab)
- git.kernel.org/stable/c/8e8be63465a5e80394c70324603dfea1bfdad48f (opens in a new tab)
- git.kernel.org/stable/c/7398ebefbfd4f8a31d4f665a4213302fa995494b (opens in a new tab)
- git.kernel.org/stable/c/4babc2d9fda2df43823b85d08a0180b68f1b0854 (opens in a new tab)
- git.kernel.org/stable/c/0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2480457 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-43501 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:34095 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:34094 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33900 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:27731 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:27713 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:25217 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:25191 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)