fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 45 fixed, 1 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds Add bounds checking to prevent writes past framebuffer boundaries when rendering text near screen edges. Return early if the Y position is off-screen and clip image height to screen boundary. Break from the rendering loop if the X position is off-screen. When clipping image width to fit the screen, update the character count to match the clipped width to prevent buffer size mismatches. Without the character count update, bit_putcs_aligned and bit_putcs_unaligned receive mismatched parameters where the buffer is allocated for the clipped width but cnt reflects the original larger count, causing out-of-bounds writes.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 2.6.12 and later | 5.4.302, 5.10.247, 5.15.197, 6.1.159, 6.6.117, 6.12.58, 6.17.8, 6.18 | Patch available | CNA |
- Linux VendorLinux Affected 2.6.12 and later Fixed in 5.4.302, 5.10.247, 5.15.197, 6.1.159, 6.6.117, 6.12.58, 6.17.8, 6.18 Patch available CNA
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.4.302, 5.10.247, 5.15.197, 6.1.159, 6.6.117, 6.12.58, 6.17.8, 6.18
Red Hat 15 advisories
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- Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4) bpftool-4.18.0-305.186.1.el8_4, kernel-4.18.0-305.186.1.el8_4, kernel-abi-stablelists-4.18.0-305.186.1.el8_4 +14
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- Red Hat Enterprise Linux RT (v. 8) kernel-rt-4.18.0-553.105.1.rt7.446.el8_10, kernel-rt-core-4.18.0-553.105.1.rt7.446.el8_10, kernel-rt-debug-4.18.0-553.105.1.rt7.446.el8_10 +7
- RHSA-2026:2766 Released 2026-02-17 · Red Hat rating Moderatekernel security update
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- Red Hat Enterprise Linux Real Time for NFV EUS (v.9.4) kernel-rt-5.14.0-427.111.1.el9_4, kernel-rt-core-5.14.0-427.111.1.el9_4, kernel-rt-debug-5.14.0-427.111.1.el9_4 +11
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Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat CodeReady Linux Builder EUS (v.9.4) | Fixed | RHSA-2026:2766 |
| Red Hat CodeReady Linux Builder EUS (v.9.6) | Fixed | RHSA-2026:2759 |
| Red Hat Enterprise Linux AppStream (v. 10) | Fixed | RHSA-2026:2282 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2026:2722 |
| Red Hat Enterprise Linux AppStream E4S (v.9.0) | Fixed | RHSA-2026:2573 |
| Red Hat Enterprise Linux AppStream E4S (v.9.2) | Fixed | RHSA-2026:2560 |
| Red Hat Enterprise Linux AppStream EUS (v. 10.0) | Fixed | RHSA-2026:1727 |
| Red Hat Enterprise Linux AppStream EUS (v.9.4) | Fixed | RHSA-2026:2766 |
| Red Hat Enterprise Linux AppStream EUS (v.9.6) | Fixed | RHSA-2026:2759 |
| Red Hat Enterprise Linux BaseOS (v. 10) | Fixed | RHSA-2026:2282 |
| Red Hat Enterprise Linux BaseOS (v. 8) | Fixed | RHSA-2026:2720 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2026:2722 |
| Red Hat Enterprise Linux BaseOS AUS (v. 8.2) | Fixed | RHSA-2026:2664 |
| Red Hat Enterprise Linux BaseOS AUS (v.8.4) | Fixed | RHSA-2026:3360 |
| Red Hat Enterprise Linux BaseOS AUS (v.8.6) | Fixed | RHSA-2026:2490 |
| Red Hat Enterprise Linux BaseOS E4S (v.8.6) | Fixed | RHSA-2026:2490 |
| Red Hat Enterprise Linux BaseOS E4S (v.8.8) | Fixed | RHSA-2026:2535 |
| Red Hat Enterprise Linux BaseOS E4S (v.9.0) | Fixed | RHSA-2026:2573 |
| Red Hat Enterprise Linux BaseOS E4S (v.9.2) | Fixed | RHSA-2026:2560 |
| Red Hat Enterprise Linux BaseOS EUS (v. 10.0) | Fixed | RHSA-2026:1727 |
| Red Hat Enterprise Linux BaseOS EUS (v.9.4) | Fixed | RHSA-2026:2766 |
| Red Hat Enterprise Linux BaseOS EUS (v.9.6) | Fixed | RHSA-2026:2759 |
| Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4) | Fixed | RHSA-2026:3360 |
| Red Hat Enterprise Linux BaseOS TUS (v.8.6) | Fixed | RHSA-2026:2490 |
| Red Hat Enterprise Linux BaseOS TUS (v.8.8) | Fixed | RHSA-2026:2535 |
| Red Hat Enterprise Linux CRB (v. 8) | Fixed | RHSA-2026:2720 |
| Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) | Fixed | RHSA-2026:2282 |
| Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) | Fixed | RHSA-2026:2722 |
| Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) | Fixed | RHSA-2026:1727 |
| Red Hat Enterprise Linux NFV (v. 8) | Fixed | RHSA-2026:2821 |
| Red Hat Enterprise Linux NFV E4S (v.9.0) | Fixed | RHSA-2026:2577 |
| Red Hat Enterprise Linux RT (v. 8) | Fixed | RHSA-2026:2821 |
| Red Hat Enterprise Linux Real Time (v. 10) | Fixed | RHSA-2026:2282 |
| Red Hat Enterprise Linux Real Time (v. 9) | Fixed | RHSA-2026:2722 |
| Red Hat Enterprise Linux Real Time E4S (v.9.0) | Fixed | RHSA-2026:2577 |
| Red Hat Enterprise Linux Real Time E4S (v.9.2) | Fixed | RHSA-2026:2583 |
| Red Hat Enterprise Linux Real Time EUS (v. 10.0) | Fixed | RHSA-2026:1727 |
| Red Hat Enterprise Linux Real Time EUS (v.9.4) | Fixed | RHSA-2026:2766 |
| Red Hat Enterprise Linux Real Time EUS (v.9.6) | Fixed | RHSA-2026:2759 |
| Red Hat Enterprise Linux Real Time for NFV (v. 10) | Fixed | RHSA-2026:2282 |
| Red Hat Enterprise Linux Real Time for NFV (v. 9) | Fixed | RHSA-2026:2722 |
| Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2) | Fixed | RHSA-2026:2583 |
| Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) | Fixed | RHSA-2026:1727 |
| Red Hat Enterprise Linux Real Time for NFV EUS (v.9.4) | Fixed | RHSA-2026:2766 |
| Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6) | Fixed | RHSA-2026:2759 |
Not affected: 2 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
Timeline
- 2026-10-02 Threatist record created from CVE-2025-40304
- 2026-10-03 Alias added: GHSA-6cgq-9674-3xfg
References
Other 8
- https://git.kernel.org/stable/c/996bfaa7372d6718b6d860bdf78f6618e850c702
- https://git.kernel.org/stable/c/f0982400648a3e00580253e0c48e991f34d2684c
- https://git.kernel.org/stable/c/1943b69e87b0ab35032d47de0a7fca9a3d1d6fc1
- https://git.kernel.org/stable/c/ebc0730b490c7f27340b1222e01dd106e820320d
- https://git.kernel.org/stable/c/86df8ade88d290725554cefd03101ecd0fbd3752
- https://git.kernel.org/stable/c/15ba9acafb0517f8359ca30002c189a68ddbb939
- https://git.kernel.org/stable/c/2d1359e11674ed4274934eac8a71877ae5ae7bbb
- https://git.kernel.org/stable/c/3637d34b35b287ab830e66048841ace404382b67
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Sources
- CVE-2025-40304 · CVE Program
- CVE-2025-40304 · NVD
- FIRST EPSS
- GHSA-6cgq-9674-3xfg · GitHub Advisory Database · CC BY 4.0
- CVE-2025-40304 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences