CVE-2026-55564

MEDIUMPre-NVD 5.45.4—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 82% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 4 sources updated this weekElevated
5.4EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.4Exploit: Elevated riskExposed: 0

A fix is available — apply it.

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, the glyph_cache_get function in libfreerdp/cache/glyph.c checks whether index is greater than cache->number instead of greater than or equal to it. A malicious RDP server can use GLYPH_FRAGMENT_USE replay in update_process_glyph_fragments to make the default cache receive index 254 when cache->number is 254, reading one pointer beyond the entries array and dereferencing it as a glyph. This can crash the client and may disclose adjacent heap data. This issue is fixed in version 3.27.0.

CVSS v3
5.4
EG Score
5.4(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: Track

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
Severity54% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
18%
KEV
Not listed

Published

August 19, 2026

Last Modified

August 25, 2026

Advisory Details (4)

Auto-updated Aug 19, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_pr, github_release, github.
github Patch Available🟡 PoC Available

Out-of-bounds read in glyph_cache_get via crafted glyph fragments · Advisory · FreeRDP/FreeRDP · GitHub

https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-6xmj-pr98-cx4c
github_release Patch Available

3.27.0

Patch available: FreeRDP/FreeRDP 3.27.0

https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0
github_pr

[cache,glyph] tighten bounds checks

Fix merged in FreeRDP/FreeRDP PR #12885 on 2026-06-13 — awaiting tagged release

https://github.com/FreeRDP/FreeRDP/pull/12885
github_commit

commit c29324750e3c (FreeRDP/FreeRDP)

Fix landed in FreeRDP/FreeRDP commit c29324750e3c — awaiting tagged release

https://github.com/FreeRDP/FreeRDP/commit/c29324750e3cbcba8761f147b7a5235cc686930f

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuwinpr3-utils (3.30.0+dfsg-0ubuntu0.26.04.1) @ resolute2026-08-26ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(2)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 23× in last 7d / 23× 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. 2026-08-26 03:47 UTCEG score recompute
  2. 2026-08-26 03:47 UTCVendor advisory
  3. 2026-08-25 13:49 UTCEPSS rescore
  4. 2026-08-25 04:24 UTCEG score recompute
  5. 2026-08-25 04:24 UTCVendor advisory
  6. 2026-08-25 03:50 UTCEG score recompute
  7. 2026-08-25 03:50 UTCVendor advisory
  8. 2026-08-24 15:17 UTCEG score recompute
  9. 2026-08-24 15:17 UTCVendor advisory
  10. 2026-08-23 15:53 UTCEG score recompute
  11. 2026-08-23 15:53 UTCVendor advisory
  12. 2026-08-23 00:19 UTCEPSS rescore
  13. 2026-08-22 16:30 UTCEG score recompute
  14. 2026-08-22 16:30 UTCVendor advisory
  15. 2026-08-21 23:49 UTCEPSS rescore
  16. 2026-08-21 17:06 UTCEG score recompute
  17. 2026-08-20 22:55 UTCEPSS rescore
  18. 2026-08-20 17:41 UTCVendor advisory
  19. 2026-08-19 18:18 UTCEG score recompute
  20. 2026-08-19 18:18 UTCVendor advisory
  21. 2026-08-19 17:53 UTCEG score recompute
  22. 2026-08-19 17:53 UTCVendor advisory
  23. 2026-08-19 17:52 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-55564?
CVE-2026-55564 is a medium vulnerability published on August 19, 2026. FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, the glyphcacheget function in libfreerdp/cache/glyph.c checks whether index is greater than cache->number instead of greater than or equal to it. A malicious RDP server can use GLYPHFRAGMENTUSE replay in…
When was CVE-2026-55564 disclosed?
CVE-2026-55564 was first published in the National Vulnerability Database on August 19, 2026, with the most recent update on August 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55564 actively exploited?
CVE-2026-55564 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 82.0% of all scored CVEs.
What is the CVSS score of CVE-2026-55564?
CVE-2026-55564 has a CVSS v3 base score of 5.4 (NVD).
How do I remediate CVE-2026-55564?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55564, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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