CVE-2026-80578: Linux kernel · fbdev: core: Fix pointer desynchronization in fb_io_read()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.3 High.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 1% 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:L/A:HExploitation evidence
Disclosed: evidence found.
CVE published 26 Aug 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 has been implemented in the Linux kernel to address this vulnerability by modifying fb_io_read() to break out of the read loop upon a partial copy_to_user(). Users should apply the official kernel updates that include this patch. Since this is a kernel-level issue, updating to the patched kernel version is the recommended mitigation.
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.
References
- nvd.nist.gov/vuln/detail/CVE-2026-80578 (opens in a new tab)
- git.kernel.org/stable/c/42a6d8126c194133eafab2b0fd5c8668ebfcba5b (opens in a new tab)
- git.kernel.org/stable/c/42bc07b4e5a3c8a02a433388f562a8f46d093e11 (opens in a new tab)
- git.kernel.org/stable/c/7110b7b794a2aac2c5cf8eb06ebf2af724c74d50 (opens in a new tab)
- git.kernel.org/stable/c/7ff87a01ae3a8cd0208f7499386998223a8b5dba (opens in a new tab)
- git.kernel.org/stable/c/81cc73be40c6f028f1ee3f438ace46afe666dbae (opens in a new tab)
- ubuntu.com/security/CVE-2026-80578 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-80578 (opens in a new tab)