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CVE-2026-80578

HIGHCVSS 7.3/10

Last modified

CVE-2026-80578 is a high-severity vulnerability rated 7.3/10 on the CVSS scale. In the Linux kernel, the following vulnerability has been resolved: fbdev: core: Fix pointer desynchronization in fb_io_read() In fb_io_read(), if copy_to_user() performs a partial copy (e.g., due to a faulty user buffer), the loop adjusts the chunk size 'c' and updates the remaining 'count'. However, the hardware 'src' pointer has already been eagerly advanced by the original chunk size. If the loop is allowed to continue, the read will resume from an incorrect, over-advanced offset.

Description

In the Linux kernel, the following vulnerability has been resolved: fbdev: core: Fix pointer desynchronization in fb_io_read() In fb_io_read(), if copy_to_user() performs a partial copy (e.g., due to a faulty user buffer), the loop adjusts the chunk size 'c' and updates the remaining 'count'. However, the hardware 'src' pointer has already been eagerly advanced by the original chunk size. If the loop is allowed to continue, the read will resume from an incorrect, over-advanced offset. Since the remaining 'count' was only decremented by the successful bytes, this desynchronization causes the next iterations to execute more hardware reads than originally bounded, eventually leading to out-of-bounds I/O reads. Fix this by breaking out of the loop immediately upon a partial copy_to_user(). A partial copy indicates a faulty user buffer, making subsequent read attempts futile. Breaking out ensures we return the number of successfully read bytes without risking out-of-bounds hardware accesses in subsequent mismatched iterations.

Metrics

CVSS 3.1
7.3/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff, < 42bc07b4e5a3c8a02a433388f562a8f46d093e11; >= 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff, < 42a6d8126c194133eafab2b0fd5c8668ebfcba5b; >= 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff, < 7ff87a01ae3a8cd0208f7499386998223a8b5dba; >= 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff, < 7110b7b794a2aac2c5cf8eb06ebf2af724c74d50; >= 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff, < 81cc73be40c6f028f1ee3f438ace46afe666dbae
LinuxLinux6.5

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-80578?
In the Linux kernel, the following vulnerability has been resolved: fbdev: core: Fix pointer desynchronization in fb_io_read() In fb_io_read(), if copy_to_user() performs a partial copy (e.g., due to a faulty user buffer), the loop adjusts the chunk size 'c' and updates the remaining 'count'. However, the hardware 'src' pointer has already been eagerly advanced by the original chunk size. If the loop is allowed to continue, the read will resume from an incorrect, over-advanced offset. Since the remaining 'count' was only decremented by the successful bytes, this desynchronization causes the next iterations to execute more hardware reads than originally bounded, eventually leading to out-of-bounds I/O reads. Fix this by breaking out of the loop immediately upon a partial copy_to_user(). A partial copy indicates a faulty user buffer, making subsequent read attempts futile. Breaking out ensures we return the number of successfully read bytes without risking out-of-bounds hardware accesses in subsequent mismatched iterations.
How severe is CVE-2026-80578?
CVE-2026-80578 has a CVSS score of 7.3/10 (HIGH severity).
How do I fix CVE-2026-80578?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST