CVE-2025-40322: Linux kernel · fbdev: bitblit: bound-check glyph index in bit_putcs*
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.1 High · fixed in 5.15.0-1103.110~20.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 11:42 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1103.110~20.04.1, 5.15.0-1110.119~20.04.1, 5.15.0-1114.123~20.04.1 +66
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 8 Dec 2025
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 25.10linuxpkg:deb/ubuntu/linux@6.17.0-14.14?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1007.7?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1008.8?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1007.7?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1007.7?arch=source&distro=questingOther 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. The Ubuntu security advisory USN-8029-1 confirms that this and several other kernel vulnerabilities have been fixed in updated kernel packages. Users should upgrade to the fixed kernel versions as listed in the advisory to remediate this issue.
Description
A vulnerability in the Linux kernel's framebuffer device (fbdev) bitblit code allowed out-of-bounds reads due to improper bounds checking of glyph indices in bit_putcs_aligned() and bit_putcs_unaligned(). This flaw was fixed by clamping the glyph index to the actual glyph count, preventing reads past the end of the built-in font array. The issue was reported by syzbot and affects certain Linux kernel versions prior to specific patched releases.
References
- ubuntu.com/security/CVE-2025-40322 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-40322 (opens in a new tab)
- git.kernel.org/linus/18c4ef4e765a798b47980555ed665d78b71aeadf (opens in a new tab)
- git.kernel.org/stable/c/0998a6cb232674408a03e8561dc15aa266b2f53b (opens in a new tab)
- git.kernel.org/stable/c/18c4ef4e765a798b47980555ed665d78b71aeadf (opens in a new tab)
- git.kernel.org/stable/c/901f44227072be60812fe8083e83e1533c04eed1 (opens in a new tab)
- git.kernel.org/stable/c/9ba1a7802ca9a2590cef95b253e6526f4364477f (opens in a new tab)
- git.kernel.org/stable/c/a10cede006f9614b465cf25609a8753efbfd45cc (opens in a new tab)
- git.kernel.org/stable/c/c12003bf91fdff381c55ef54fef3e961a5af2545 (opens in a new tab)
- git.kernel.org/stable/c/db5c9a162d2f42bcc842b76b3d935dcc050a0eec (opens in a new tab)
- git.kernel.org/stable/c/efaf89a75a29b2d179bf4fe63ca62852e93ad620 (opens in a new tab)
- ubuntu.com/security/notices/USN-8029-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8030-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8029-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8048-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8029-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8095-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8096-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8100-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8095-2 (opens in a new tab)