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CVE-2026-22858

Freerdp buffer overflow

9.1 CRITICALPublic exploitEPSS 0.69%
  1. Published14 Jan 2026

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected products

Freerdp< 3.20.1

Remediation

Fixed in
Freerdp≥ 3.20.1

References

and 9 more references

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Frequently asked

Is CVE-2026-22858 being actively exploited?

CVE-2026-22858 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.69%.

How severe is CVE-2026-22858?

CVE-2026-22858 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.69% probability of exploitation.

Which products are affected by CVE-2026-22858?

Affected products include Freerdp.

How do I fix CVE-2026-22858?

Upgrade affected software to a fixed version, for example Freerdp 3.20.1 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-22858 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.