CVE-2026-55564

HIGHNVD 7.17.1—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.1 under NVD CVSS v3. EPSS exploit probability: 0.4% (36th percentile of EPSS-scored CVEs). 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, nvd
Trending — 3 sources updated this weekElevated
7.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 7.1Exploit: Elevated riskExposed services: Not assessed

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
7.1
EG Score
7.1HIGHmedium confidence
EG Risk
48
EG Risk 48/100CISA 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
Severity71% × 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
0.4%
EPSS %ILE
36th
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

August 19, 2026

Last Modified

September 22, 2026

Advisory Details (4)

Auto-updated Aug 19, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_pr, github_release, github.
githubMentions a patch (unverified)🟡 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 / EcosystemFix (by version range) / PatchReleasedSource
ubuntuwinpr3-utils (3.30.0+dfsg-0ubuntu0.24.04.1) @ noble2026-10-08ubuntu

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.

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
freerdp22.10.0+dfsg1-1 ... 2.11.7+dfsg1-6~deb12u1 (13 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
freerdp33.15.0+dfsg-2.1 ... 3.31.1+dfsg-1~bpo13+1 (46 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
freerdp33.15.0+dfsg-2.1 ... 3.26.0+dfsg-1~bpo13+1 (33 versions)
  • every version up to 3.27.0+dfsg-1: fixed in 3.27.0+dfsg-1
—

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 20× in last 7d / 85× 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.

Showing the most recent 100 of 145 total refreshes for this CVE.

  1. 2026-10-09 20:07 UTCEPSS rescore
  2. 2026-10-08 17:12 UTCEPSS rescore
  3. 2026-10-08 07:44 UTCEG score recompute
  4. 2026-10-08 07:44 UTCVendor advisory
  5. 2026-10-07 23:48 UTCEPSS rescore
  6. 2026-10-07 10:26 UTCVendor advisory
  7. 2026-10-06 21:21 UTCEG score recompute
  8. 2026-10-06 21:21 UTCVendor advisory
  9. 2026-10-06 15:18 UTCEPSS rescore
  10. 2026-10-06 07:57 UTCEG score recompute
  11. 2026-10-06 07:57 UTCVendor advisory
  12. 2026-10-05 17:43 UTCEPSS rescore
  13. 2026-10-05 09:58 UTCEG score recompute
  14. 2026-10-05 09:58 UTCVendor advisory
  15. 2026-10-04 23:22 UTCEPSS rescore
  16. 2026-10-04 21:24 UTCVendor advisory
  17. 2026-10-04 05:28 UTCVendor advisory
  18. 2026-10-03 16:55 UTCEG score recompute
  19. 2026-10-03 16:55 UTCVendor advisory
  20. 2026-10-03 14:26 UTCEPSS rescore
  21. 2026-10-03 01:37 UTCEG score recompute
  22. 2026-10-03 01:37 UTCVendor advisory
  23. 2026-10-02 17:56 UTCEPSS rescore
  24. 2026-10-02 12:57 UTCVendor advisory
  25. 2026-10-01 22:46 UTCEG score recompute
Show 75 more
  1. 2026-10-01 22:46 UTCVendor advisory
  2. 2026-10-01 19:50 UTCEPSS rescore
  3. 2026-10-01 09:52 UTCVendor advisory
  4. 2026-09-30 21:18 UTCEG score recompute
  5. 2026-09-30 21:18 UTCVendor advisory
  6. 2026-09-30 15:03 UTCEPSS rescore
  7. 2026-09-30 08:43 UTCEG score recompute
  8. 2026-09-30 08:43 UTCVendor advisory
  9. 2026-09-29 15:22 UTCEPSS rescore
  10. 2026-09-28 21:42 UTCEG score recompute
  11. 2026-09-28 21:42 UTCVendor advisory
  12. 2026-09-28 13:51 UTCEPSS rescore
  13. 2026-09-28 08:08 UTCVendor advisory
  14. 2026-09-27 19:29 UTCEG score recompute
  15. 2026-09-27 19:29 UTCVendor advisory
  16. 2026-09-27 13:48 UTCEPSS rescore
  17. 2026-09-27 06:55 UTCEG score recompute
  18. 2026-09-27 06:55 UTCVendor advisory
  19. 2026-09-26 15:59 UTCEPSS rescore
  20. 2026-09-25 00:51 UTCEG score recompute
  21. 2026-09-25 00:51 UTCVendor advisory
  22. 2026-09-24 14:04 UTCEPSS rescore
  23. 2026-09-24 08:42 UTCVendor advisory
  24. 2026-09-23 20:09 UTCEG score recompute▲ 1.70
  25. 2026-09-23 20:09 UTCVendor advisory
  26. 2026-09-23 17:54 UTCEPSS rescore
  27. 2026-09-22 19:51 UTCNVD updateCVSS v3 → 7.1 · severity → HIGH
  28. 2026-09-22 19:50 UTCEG score recompute
  29. 2026-09-22 19:50 UTCVendor advisory
  30. 2026-09-21 19:56 UTCVendor advisory
  31. 2026-09-20 20:32 UTCEG score recompute
  32. 2026-09-20 20:32 UTCVendor advisory
  33. 2026-09-20 20:16 UTCEPSS rescore
  34. 2026-09-19 21:09 UTCEG score recompute
  35. 2026-09-19 21:09 UTCVendor advisory
  36. 2026-09-18 21:45 UTCEG score recompute
  37. 2026-09-18 21:45 UTCVendor advisory
  38. 2026-09-18 19:28 UTCEPSS rescore
  39. 2026-09-17 21:30 UTCEG score recompute
  40. 2026-09-17 21:30 UTCVendor advisory
  41. 2026-09-17 19:31 UTCEPSS rescore
  42. 2026-09-16 20:06 UTCEG score recompute
  43. 2026-09-16 20:06 UTCVendor advisory
  44. 2026-09-16 14:08 UTCEPSS rescore
  45. 2026-09-16 05:15 UTCEPSS rescore
  46. 2026-09-15 19:05 UTCEG score recompute
  47. 2026-09-15 19:05 UTCVendor advisory
  48. 2026-09-15 03:11 UTCEPSS rescore
  49. 2026-09-14 19:34 UTCVendor advisory
  50. 2026-09-13 20:11 UTCEG score recompute
  51. 2026-09-13 20:11 UTCVendor advisory
  52. 2026-09-13 16:47 UTCEPSS rescore
  53. 2026-09-12 20:48 UTCEG score recompute
  54. 2026-09-12 20:48 UTCVendor advisory
  55. 2026-09-11 21:25 UTCEG score recompute
  56. 2026-09-11 21:25 UTCVendor advisory
  57. 2026-09-11 14:53 UTCEPSS rescore
  58. 2026-09-10 22:00 UTCEG score recompute
  59. 2026-09-10 22:00 UTCVendor advisory
  60. 2026-09-10 09:35 UTCEPSS rescore
  61. 2026-09-09 22:36 UTCVendor advisory
  62. 2026-09-09 02:35 UTCEG score recompute
  63. 2026-09-09 02:35 UTCVendor advisory
  64. 2026-09-08 22:01 UTCEPSS rescore
  65. 2026-09-07 20:02 UTCEG score recompute
  66. 2026-09-07 20:02 UTCVendor advisory
  67. 2026-09-07 16:01 UTCEPSS rescore
  68. 2026-09-06 20:38 UTCEG score recompute
  69. 2026-09-06 20:38 UTCVendor advisory
  70. 2026-09-06 13:47 UTCEPSS rescore
  71. 2026-09-05 21:13 UTCEG score recompute
  72. 2026-09-05 21:13 UTCVendor advisory
  73. 2026-09-04 21:50 UTCEG score recompute
  74. 2026-09-04 21:50 UTCVendor advisory
  75. 2026-09-04 05:06 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2026-55564?
CVE-2026-55564 is a high 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 on August 19, 2026, with the most recent update on September 22, 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 0.4% probability of exploitation in the next 30 days (36th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55564?
CVE-2026-55564 has a CVSS v3 base score of 7.1 (NVD).
How do I remediate CVE-2026-55564?
A fix for CVE-2026-55564 is available: update to the fixed version the vendor names in its advisory.

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