CVE-2026-91958

MEDIUMPre-NVD 6.66.6—
EchelonGraph scoreHIGH confidence

Score 6.6 from GitHub Security Advisory published 2026-09-15. A secondary CVSS source baseline 6.6; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this weekElevated
6.6EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 6.6Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

FreeRDP versions before 3.31.0 fail to validate MonitorIds array values when parsing RDP connection files, allowing unbounded array indexing in xf_detect_monitors. Attackers can craft a malicious RDP file with an out-of-range selectedmonitors value to trigger out-of-bounds heap read and write operations when opened in xfreerdp.

CVSS v3
6.6
EG Score
6.6MEDIUMhigh confidence
EG Risk
46
EG Risk 46/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity66% × 45%
Exploitation40% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
8th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 15, 2026

Last Modified

September 24, 2026

Advisory Details (2)

Auto-updated Sep 15, 2026
🔬 Proof of concept available. Patch available. Sources: github.
generic

FreeRDP 3.11.0 through 3.30.0 Heap Buffer Overflow via Monitor Index | Advisories | VulnCheck

https://www.vulncheck.com/advisories/freerdp-3.11.0-through-3.30.0-heap-buffer-overflow-via-monitor-index
github Patch Available🟡 PoC Available

Unbounded `MonitorIds[0]` used as an array index in X11 monitor selection · Advisory · FreeRDP/FreeRDP · GitHub

https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-23pf-q83q-x45r

Vendor Advisories for CVE-2026-91958(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(2 across 2 ecosystems)
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
freerdp33.15.0+dfsg-2.1 ... 3.32.0+dfsg-1 (47 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
freerdp33.15.0+dfsg-2.1 ... 3.30.0+dfsg-1~bpo13+1 (40 versions)
  • every version up to 3.31.0+dfsg-1: fixed in 3.31.0+dfsg-1
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 17× in last 7d / 55× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-04 23:22 UTCEPSS rescore
  2. 2026-10-04 19:14 UTCGHSA enrichment
  3. 2026-10-03 18:52 UTCEG score recompute
  4. 2026-10-03 18:52 UTCGHSA enrichment
  5. 2026-10-02 17:52 UTCEG score recompute
  6. 2026-10-02 17:52 UTCGHSA enrichment
  7. 2026-10-01 19:51 UTCEPSS rescore
  8. 2026-10-01 17:31 UTCGHSA enrichment
  9. 2026-09-30 17:10 UTCEG score recompute
  10. 2026-09-30 17:10 UTCGHSA enrichment
  11. 2026-09-30 15:04 UTCEPSS rescore
  12. 2026-09-29 15:15 UTCEG score recompute
  13. 2026-09-29 15:15 UTCGHSA enrichment
  14. 2026-09-28 14:55 UTCEG score recompute
  15. 2026-09-28 14:55 UTCGHSA enrichment
  16. 2026-09-28 13:52 UTCEPSS rescore
  17. 2026-09-28 13:52 UTCEPSS rescore
  18. 2026-09-27 14:34 UTCEG score recompute
  19. 2026-09-27 14:34 UTCGHSA enrichment
  20. 2026-09-27 13:49 UTCEPSS rescore
  21. 2026-09-26 15:59 UTCEPSS rescore
  22. 2026-09-26 14:13 UTCEG score recompute
  23. 2026-09-26 14:13 UTCGHSA enrichment
  24. 2026-09-25 12:40 UTCEG score recompute
  25. 2026-09-25 12:40 UTCGHSA enrichment
Show 30 more
  1. 2026-09-24 14:04 UTCEPSS rescore
  2. 2026-09-24 12:19 UTCGHSA enrichment
  3. 2026-09-23 23:54 UTCEG score recompute
  4. 2026-09-23 23:54 UTCGHSA enrichment
  5. 2026-09-23 17:54 UTCEPSS rescore
  6. 2026-09-22 23:34 UTCEG score recompute
  7. 2026-09-22 23:34 UTCGHSA enrichment
  8. 2026-09-22 16:01 UTCEPSS rescore
  9. 2026-09-21 22:52 UTCEG score recompute
  10. 2026-09-21 22:52 UTCGHSA enrichment
  11. 2026-09-21 21:09 UTCEPSS rescore
  12. 2026-09-20 22:31 UTCEG score recompute
  13. 2026-09-20 22:31 UTCGHSA enrichment
  14. 2026-09-20 20:16 UTCEPSS rescore
  15. 2026-09-19 22:10 UTCEG score recompute
  16. 2026-09-19 22:10 UTCGHSA enrichment
  17. 2026-09-18 21:49 UTCEG score recompute
  18. 2026-09-18 21:49 UTCGHSA enrichment
  19. 2026-09-18 19:28 UTCEPSS rescore
  20. 2026-09-17 21:29 UTCEG score recompute
  21. 2026-09-17 21:29 UTCGHSA enrichment
  22. 2026-09-17 19:32 UTCEPSS rescore
  23. 2026-09-16 21:07 UTCGHSA enrichment
  24. 2026-09-16 17:55 UTCEG score recompute
  25. 2026-09-16 17:55 UTCGHSA enrichment
  26. 2026-09-16 14:09 UTCEPSS rescore
  27. 2026-09-15 17:32 UTCEG score recompute
  28. 2026-09-15 16:18 UTCEG score recompute
  29. 2026-09-15 15:23 UTCEG score recompute
  30. 2026-09-15 15:22 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-91958?
CVE-2026-91958 is a medium vulnerability published on September 15, 2026. FreeRDP versions before 3.31.0 fail to validate MonitorIds array values when parsing RDP connection files, allowing unbounded array indexing in xfdetectmonitors. Attackers can craft a malicious RDP file with an out-of-range selectedmonitors value to trigger out-of-bounds heap read and write…
When was CVE-2026-91958 disclosed?
CVE-2026-91958 was first published on September 15, 2026, with the most recent update on September 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-91958 actively exploited?
CVE-2026-91958 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (8th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-91958?
CVE-2026-91958 has a CVSS base score of 6.6 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-91958?
A fix for CVE-2026-91958 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-91958 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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