Evidence used
- No CISA KEV confirmation is currently recorded.
- A structured source references public exploit or proof-of-concept material.
- EPSS is 0.38% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-91959High confidence
FreeRDP before 3.31.0 Buffer Over-read via RTS Gateway
FreeRDP · FreeRDP
Official source article: GitHub GHSA-PJ8W-FH79-F438 ↗. Check the applicable product and release in the original source.
7.1HighCVSS 4.0
Patch only the product branches with a verified fix
Fix availability varies by productHigh technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 33 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:Critical, raised one band.upgradedsince 20 Sep 2026
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Increase monitoring for the attack path and post-exploitation behaviour described in the report.
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 33 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 31 affected or under-investigation product states without a fixed product state in the same current advisory
- Debian Security Tracker: 2 affected package states with no published fix
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.
Package result overrides the generic status
BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 2 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.
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 | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian bookwormbookworm · source | freerdp2 | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 5 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 5 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 5 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 4 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 4 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-2026-91959 · CSAF 2.0 · revision 3 · finalRed Hat Product SecurityFreeRDP: FreeRDP: Denial of Service due to buffer over-read in RPC gateway
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
- freerdp as a component of Red Hat Enterprise Linux 6
- freerdp-devel as a component of Red Hat Enterprise Linux 6
- freerdp-libs as a component of Red Hat Enterprise Linux 6
- freerdp-plugins as a component of Red Hat Enterprise Linux 6
- freerdp.src as a component of Red Hat Enterprise Linux 6
- Summary
- A flaw was found in FreeRDP. A remote attacker can exploit a buffer over-read vulnerability within the RPC (Remote Procedure Call) gateway transport parser by sending a malicious BIND_ACK Protocol Data Unit (PDU) with a truncated result entry. This can lead to a process abort, resulting in a Denial of Service (DoS).
- Remediation
- To mitigate this issue, restrict network access to any FreeRDP instance operating in a server or gateway role, limiting connections to trusted clients or networks. If FreeRDP is used as a client, avoid connecting to untrusted or malicious RDP servers to prevent exploitation.
High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 33 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 before 3.31.0 contains a buffer over-read vulnerability in the rts_read_result function within the RPC gateway transport parser. Attackers can send a malicious BIND_ACK PDU with a truncated result entry to trigger an out-of-bounds read causing process abort.
What
FreeRDP before 3.31.0 contains a buffer over-read vulnerability in the rts_read_result function within the RPC gateway transport parser. Attackers can send a malicious BIND_ACK PDU with a truncated result entry to trigger an out-of-bounds read causing process abort.
Why
The product reads data past the end, or before the beginning, of the intended buffer.
How
An attacker operating through a network path may attempt exploitation when the stated preconditions are met. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
FreeRDP before 3.31.0 contains a buffer over-read vulnerability in the rts_read_result function within the RPC gateway transport parser. Attackers can send a malicious BIND_ACK PDU with a truncated result entry to trigger an out-of-bounds read causing process abort.
Why
The product reads data past the end, or before the beginning, of the intended buffer.
How
An attacker operating through a network path may attempt exploitation when the stated preconditions are met. 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 Reference recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.
- Likely attack path
- a network path → Out-of-bounds Read → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- Passive interaction required
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Not a CVSS 4.0 base metric
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-125 ↗
CWE-125: Out-of-bounds Read. The product reads data past the end, or before the beginning, of the intended buffer.
- 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:L/AT:N/PR:N/UI:P/VC:N/VI:N/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.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIPassiveUser interaction: A user must unknowingly interact with the vulnerable system.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VINoneVulnerable-system integrity: No direct loss is represented by this metric.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
- freerdp as a component of Red Hat Enterprise Linux 6
- freerdp-devel as a component of Red Hat Enterprise Linux 6
- freerdp-libs as a component of Red Hat Enterprise Linux 6
- freerdp-plugins as a component of Red Hat Enterprise Linux 6
- freerdp.src as a component of Red Hat Enterprise Linux 6
- freerdp as a component of Red Hat Enterprise Linux 7
- freerdp-devel as a component of Red Hat Enterprise Linux 7
- freerdp-libs as a component of Red Hat Enterprise Linux 7
- freerdp-plugins as a component of Red Hat Enterprise Linux 7
- freerdp.src as a component of Red Hat Enterprise Linux 7
- libwinpr as a component of Red Hat Enterprise Linux 7
- libwinpr-devel as a component of Red Hat Enterprise Linux 7
- freerdp as a component of Red Hat Enterprise Linux 8
- freerdp-devel as a component of Red Hat Enterprise Linux 8
- freerdp-libs as a component of Red Hat Enterprise Linux 8
- freerdp.src as a component of Red Hat Enterprise Linux 8
- libwinpr as a component of Red Hat Enterprise Linux 8
- libwinpr-devel as a component of Red Hat Enterprise Linux 8
- freerdp as a component of Red Hat Enterprise Linux 9
- freerdp-devel as a component of Red Hat Enterprise Linux 9
- freerdp-libs as a component of Red Hat Enterprise Linux 9
- freerdp.src as a component of Red Hat Enterprise Linux 9
- libwinpr as a component of Red Hat Enterprise Linux 9
- and 1 more
- 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 any FreeRDP instance operating in a server or gateway role, limiting connections to trusted clients or networks. If FreeRDP is used as a client, avoid connecting to untrusted or malicious RDP servers to prevent exploitation.
Official vendor articles1 stored document
Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.
- `rts_read_result()` length-checks 2 bytes and then reads 4 — a truncated BIND_ACK result list aborts any client using the RPC gateway transport · Advisory · FreeRDP/FreeRDP · GitHub →Original publisher ↗Searchable text snapshot · Captured 26 Sep 2026FreeRDP / FreeRDP Public Notifications You must be signed in to change notification settings Fork 15.5k Star 13.7k Code Issues 143 Pull requests 23 Discussions Actions Projects Wiki Security and quality 212 Insights Additional navigation options Code Issues Pull requests Discussions Actions Projects
04
Evidence and provenance
Published 15 Sept 2026 · Last source change 20 Sept 2026, 00:35 UTC · CWE-125 · Out-of-bounds Read
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-2026-78635
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD enriched
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Vendor guidanceAuthoritative vendor guidance changed: added mitigation: github.com/GHSA-pj8w-fh79-f438.disclosure@vulncheck.com ↗
- Before
- remediation: github.com/GHSA-pj8w-fh79-f438
- After
- mitigation: github.com/GHSA-pj8w-fh79-f438 · remediation: github.com/GHSA-pj8w-fh79-f438
- Public exploit evidencePublic exploit evidence changed from Public exploit reference to Public exploit reference.disclosure@vulncheck.com ↗
- Before
- Public exploit reference
- After
- Public exploit reference
- ENISA EUVD mappingEUVD-2026-78635 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-78635"}
- 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.