CVE-2026-90042: Linux kernel · ceph: properly decrypt filenames in vmalloc() buffers
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 42% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
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 16 Sep 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
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 fix is available that properly handles vmalloc()-allocated buffers in the Ceph filename decryption code by using a bounce buffer to ensure linear address mapping. Systems running affected Linux kernel versions should apply the official patches or updates that include this fix. The overhead introduced by the fix is minimal and only affects a small subset of messages. No additional mitigation steps are indicated by the vendor advisory.
Description
A vulnerability in the Linux kernel's Ceph filesystem component was resolved by properly handling filename decryption in vmalloc() buffers. The issue arose because the fscrypt subsystem requires buffers to be in the linear mapping region, but Ceph's messenger client sometimes uses kvmalloc(), which can allocate buffers in the vmalloc() region. This mismatch caused kernel oopses, especially on non-x86 platforms. The fix makes the ceph_fname_to_usr() function tolerant of vmalloc()-allocated buffers by using a bounce buffer when necessary, preventing improper address usage in fscrypt. This fix introduces minor overhead only when processing a small fraction of messages that spill into vmalloc().