CVE-2026-63868: Linux kernel · net: garp: fix unsigned integer underflow in garp_pdu_parse_attr
Affects Linux kernelSource GCVE Database
Not known to be exploited · fixed in 5.15.0-1117.124~20.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 12:55 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +67
Exploitation evidence
Disclosed: evidence found.
CVE published 19 Jul 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-gkepkg:deb/ubuntu/linux-gke?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 to affected Linux kernel versions to correct the unsigned integer underflow in the GARP attribute parser. Refer to the vendor advisory (Ubuntu Security Notice USN-8726-1) for updated kernel packages and apply them accordingly.
Description
A vulnerability in the Linux kernel's GARP attribute parser caused an unsigned integer underflow due to incorrect computation of attribute data length. This flaw disrupted the processing of GARP Join/Leave events, affecting VLAN registration attributes. The issue has been fixed in updated Linux kernel versions.
References
- nvd.nist.gov/vuln/detail/CVE-2026-63868 (opens in a new tab)
- git.kernel.org/stable/c/04e22fefac1af3e32f245e9045382348773b5d59 (opens in a new tab)
- git.kernel.org/stable/c/16e408e607a94b646fb14a2a98422c6877ae4b3c (opens in a new tab)
- git.kernel.org/stable/c/29f28172afb2ae7b31e9bf3e978396f20b381688 (opens in a new tab)
- git.kernel.org/stable/c/74e02121be1dcc0efcd56ebdf0171d6129105659 (opens in a new tab)
- git.kernel.org/stable/c/973cf7c433d27f4d9556d0b7c332543be7ed7a6e (opens in a new tab)
- git.kernel.org/stable/c/a11f1a671b1361f0f1278dc0041374f2730df73f (opens in a new tab)
- git.kernel.org/stable/c/d4c86ea09ae3e63ee5aa86e941fcc38e0e39874a (opens in a new tab)
- git.kernel.org/stable/c/d8dcd14aa886b8effd83022c550669f4f262854b (opens in a new tab)
- ubuntu.com/security/CVE-2026-63868 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-63868 (opens in a new tab)
- git.kernel.org/linus/16e408e607a94b646fb14a2a98422c6877ae4b3c (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8727-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8760-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8800-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8760-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8878-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8879-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8877-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8903-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8905-1 (opens in a new tab)