CVE-2026-99180: Linux kernel · unicode: free the map after a grace period
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 29 Oct 2026, 22:46 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
Thin evidence
One scorer or noneExploitation evidence
Disclosed: evidence found.
CVE published 28 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 29 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10linuxpkg:deb/ubuntu/linux?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=stonkingOther 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 fix is available that delays freeing the unicode map until after an RCU grace period has passed, preventing use-after-free during pathwalks. Users should apply the updated Linux kernel versions that include this patch. No additional mitigation actions are indicated.
Description
CVE-2026-99180 is a use-after-free vulnerability in the Linux kernel's unicode handling code affecting filesystems such as ext4, f2fs, and tmpfs. The issue arises because the unicode map is freed immediately after the last reference to a mount goes away, but ongoing pathwalks in RCU mode may still access the freed map, leading to a kernel memory corruption detected by KASAN. The vulnerability is reachable when a mount's last reference is dropped outside of umount(2), such as closing a file or changing directories out of a lazily unmounted directory. The fix delays freeing the unicode map until after a grace period to ensure no pathwalks access freed memory.
References
- ubuntu.com/security/CVE-2026-99180 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-99180 (opens in a new tab)
- git.kernel.org/stable/c/a96c5299bd7305eb984377681eb3222a57376405 (opens in a new tab)
- git.kernel.org/stable/c/6560c3d9a6925e3747d9ad8463e16010c31ba715 (opens in a new tab)
- git.kernel.org/stable/c/2b54d3c971a1e5df3c9b0bcc10311ae6c29e79d8 (opens in a new tab)