CVE-2026-43501: Linux kernel · ipv6: rpl: reserve mac_len headroom when recompressed SRH grows
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 5.15.0-1111.118~20.04.1 : 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 5.15.0-1111.118~20.04.1, 5.15.0-1116.125~20.04.1, 5.15.0-1111.121~20.04.1 +86
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 |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-ibmpkg:deb/ubuntu/linux-ibm?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available and should be applied promptly. The fix expands the headroom in the skb buffer during IPv6 SRH processing to prevent out-of-bounds writes. Users should update to the fixed Linux kernel versions as provided by their distribution vendors. No additional mitigations are specified beyond applying the official fix.
Description
A critical vulnerability in the Linux kernel's IPv6 routing header processing (CVE-2026-43501) allows out-of-bounds memory writes due to improper handling of headroom when recompressing Source Routing Headers (SRH). This flaw occurs when the recompressed header grows larger than the original, causing memory corruption. The issue affects specific Linux kernel versions and has been addressed by expanding the headroom appropriately during processing.
References
- ubuntu.com/security/CVE-2026-43501 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-43501 (opens in a new tab)
- git.kernel.org/linus/9e6bf146b55999a095bb14f73a843942456d1adc (opens in a new tab)
- git.kernel.org/stable/c/4babc2d9fda2df43823b85d08a0180b68f1b0854 (opens in a new tab)
- git.kernel.org/stable/c/7398ebefbfd4f8a31d4f665a4213302fa995494b (opens in a new tab)
- git.kernel.org/stable/c/8e8be63465a5e80394c70324603dfea1bfdad48f (opens in a new tab)
- git.kernel.org/stable/c/9e6bf146b55999a095bb14f73a843942456d1adc (opens in a new tab)
- git.kernel.org/stable/c/c261d07a80576dc8ccf394ef8f074f8c67a06b37 (opens in a new tab)
- ubuntu.com/security/notices/USN-8488-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8489-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8490-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8491-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8493-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8488-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8497-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8498-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8499-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8493-2 (opens in a new tab)