Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.59% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-91948High confidence
FreeRDP before 3.31.0 Out-of-bounds Write via SHOW_PROTOCOL
FreeRDP · FreeRDP
Official source article: GitHub GHSA-9JCM-X588-GH26 ↗. Check the applicable product and release in the original source.
7.7HighCVSS 4.0
Patch only the product branches with a verified fix
Fix availability varies by productHigh technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 7 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs FreeRDP FreeRDP and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 7 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 7 affected or under-investigation product states without a fixed product state in the same current advisory
Distribution package intelligence
6 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | freerdp3 | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 7 Oct 2026 |
| Debian bookwormbookworm · source | freerdp2 | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 7 Oct 2026 |
| Debian forkyforky · source | freerdp3 | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.31.0+dfsg-1 | Debian Security Tracker ↗Source updated 7 Oct 2026 |
| Debian sidsid · source | freerdp3 | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.31.0+dfsg-1 | Debian Security Tracker ↗Source updated 7 Oct 2026 |
| Ubuntu 24.04 LTSnoble · esm-apps | freerdp2 | Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 7 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | freerdp3 | Vendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree. | 3.31.0+dfsg-0ubuntu0.24.04.1 | Canonical Ubuntu Security ↗Source updated 7 Oct 2026 |
Direct vendor intelligence
1 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
CVE-2026-91948 · CSAF 2.0 · revision 3 · finalRed Hat Product SecurityFreeRDP: FreeRDP: Arbitrary code execution via oversized channel messages in SHOW_PROTOCOL
The vendor explicitly identifies these products as affected by this CVE.
- freerdp as a component of Red Hat Enterprise Linux 10
- freerdp-devel as a component of Red Hat Enterprise Linux 10
- freerdp-libs as a component of Red Hat Enterprise Linux 10
- freerdp-server as a component of Red Hat Enterprise Linux 10
- freerdp.src as a component of Red Hat Enterprise Linux 10
- libwinpr as a component of Red Hat Enterprise Linux 10
- libwinpr-devel as a component of Red Hat Enterprise Linux 10
- Summary
- A flaw was found in FreeRDP. An authenticated client can send specially crafted, oversized messages to the server when the CHANNEL_OPTION_SHOW_PROTOCOL feature is active. This can cause a buffer underflow, leading to corruption of memory and potentially allowing an attacker to execute malicious code on the server.
- Remediation
- To mitigate this issue, restrict network access to the FreeRDP server to only trusted clients or localhost. This can be achieved by configuring firewall rules to limit inbound connections to the FreeRDP service port. A restart of the FreeRDP server may be required for network configuration changes to take effect.
High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 7 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
FreeRDP versions before 3.31.0 contain an out-of-bounds write vulnerability in server-side static virtual channel handling when CHANNEL_OPTION_SHOW_PROTOCOL is enabled. Authenticated clients can queue oversized channel messages that cause buffer underflow and corrupt heap memory including live pointers, potentially enabling code execution.
What
FreeRDP versions before 3.31.0 contain an out-of-bounds write vulnerability in server-side static virtual channel handling when CHANNEL_OPTION_SHOW_PROTOCOL is enabled. Authenticated clients can queue oversized channel messages that cause buffer underflow and corrupt heap memory including live pointers, potentially enabling code execution.
Why
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
FreeRDP versions before 3.31.0 contain an out-of-bounds write vulnerability in server-side static virtual channel handling when CHANNEL_OPTION_SHOW_PROTOCOL is enabled. Authenticated clients can queue oversized channel messages that cause buffer underflow and corrupt heap memory including live pointers, potentially enabling code execution.
Why
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Integer Underflow (Wrap or Wraparound) → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- Low: a basic authenticated account is required
- User interaction
- None
- Attack complexity
- High: exploitation depends on specific conditions
- Security boundary
- Not a CVSS 4.0 base metric
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-191 ↗
CWE-191: Integer Underflow (Wrap or Wraparound). The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NCommon Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.ATPresentAttack requirements: A particular deployment or execution condition must be present.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix availability varies by product
- Affected
- freerdp as a component of Red Hat Enterprise Linux 10
- freerdp-devel as a component of Red Hat Enterprise Linux 10
- freerdp-libs as a component of Red Hat Enterprise Linux 10
- freerdp-server as a component of Red Hat Enterprise Linux 10
- freerdp.src as a component of Red Hat Enterprise Linux 10
- libwinpr as a component of Red Hat Enterprise Linux 10
- libwinpr-devel as a component of Red Hat Enterprise Linux 10
- Fixed
- FreeRDP: 3.31.0
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- Workaround
- To mitigate this issue, restrict network access to the FreeRDP server to only trusted clients or localhost. This can be achieved by configuring firewall rules to limit inbound connections to the FreeRDP service port. A restart of the FreeRDP server may be required for network configuration changes to take effect.
04
Evidence and provenance
Published 15 Sept 2026 · Last source change 17 Sept 2026, 11:59 UTC · CWE-191 · Integer Underflow (Wrap or Wraparound)
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-09-16
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-78805
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD not scheduled
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- ENISA EUVD mappingEUVD-2026-78805 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-78805"}
- Public exploit evidencePublic exploit evidence changed from Public exploit reference to No public exploit.CVE.org ↗
- Before
- Public exploit reference
- After
- No public exploit
- Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.CVE.org ↗
- Before
- No public exploit
- After
- Public exploit reference
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
CVE published
Fixed release or patch reference recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.