CVE-2026-22858: FreeRDP's Base64 decoding path · Prior to 3.20.1, global-buffer-overflow was observed
Affects freerdpSource GCVE Database
Not known to be exploited · CVSS 9.1 Critical · fixed in 3.5.1+dfsg1-0ubuntu1.4 : patch freerdp as a priority.
Data as of 27 Oct 2026, 06:42 UTC
- Patch
- Available – fixed in 3.5.1+dfsg1-0ubuntu1.4, 3.16.0+dfsg-2ubuntu0.3, 3.20.2+dfsg-1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 14 Jan 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
Upgrade the Ubuntu freerdp3 to 3.5.1+dfsg1-0ubuntu1.4 (package) or 3.16.0+dfsg-2ubuntu0.3 (package) or 3.20.2+dfsg-1 (package).
Patches and advisories
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSfreerdp3pkg:deb/ubuntu/freerdp3?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 25.10freerdp3pkg:deb/ubuntu/freerdp3?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSfreerdp3pkg:deb/ubuntu/freerdp3?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu Pro 24.04 LTSfreerdp2pkg:deb/ubuntu/freerdp2?arch=source&distro=esm-apps/nobleOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSfreerdp2pkg:deb/ubuntu/freerdp2?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu Pro 20.04 LTSfreerdp2pkg:deb/ubuntu/freerdp2?arch=source&distro=esm-infra/focalOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.20.1, global-buffer-overflow was observed in FreeRDP's Base64 decoding path. The root cause appears to be implementation-defined char signedness: on Arm/AArch64 builds, plain char is treated as unsigned, so the guard c <= 0 can be optimized into a simple c != 0 check. As a result, non-ASCII bytes (e.g., 0x80-0xFF) may bypass the intended range restriction and be used as an index into a global lookup table, causing out-of-bounds access. This vulnerability is fixed in 3.20.1.
References
- ubuntu.com/security/CVE-2026-22858 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-22858 (opens in a new tab)
- github.com/FreeRDP/FreeRDP/security/advisories/GHSA-qmqf-m84q-x896 (opens in a new tab)
- github.com/FreeRDP/FreeRDP/releases/tag/3.20.1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8105-1 (opens in a new tab)