CVE-2025-40322: Linux kernel · fbdev: bitblit: bound-check glyph index in bit_putcs*
Source GCVE Database
Not known to be exploited · CVSS 7.1 High.
Data as of 26 Oct 2026, 12:55 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.
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
AI-suggested
A fix has been implemented in the Linux kernel to clamp the glyph index to the actual glyph count, preventing out-of-bounds reads. Users and administrators should apply the official Linux kernel updates that include this patch. Since this is a kernel-level vulnerability, updating to the fixed kernel version is the recommended remediation. Patch status is not explicitly confirmed in the provided data; check the vendor or Linux kernel advisory for the exact fixed version and update accordingly.
Description
A high-severity vulnerability in the Linux kernel's framebuffer device (fbdev) bitblit code was resolved. The issue involved out-of-bounds reads caused by improper bound-checking of glyph indices in the bit_putcs_aligned() and bit_putcs_unaligned() functions. These functions derived glyph pointers from character values masked by 0xff or 0x1ff, which could exceed the actual font's glyph count, leading to reads past the end of the font array. The fix clamps the glyph index to the actual glyph count to prevent this out-of-bounds access. This vulnerability was identified and reported by syzbot. No known exploits are reported in the wild.
References
- nvd.nist.gov/vuln/detail/CVE-2025-40322 (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)