CVE-2026-63633

CRITICALNVD 9.89.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 0.6% (48th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3
Trending — 3 sources updated this weekElevated
9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 9.8Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.28.0, freerdp_dsp_decode_opus in libfreerdp/codec/dsp.c calls Stream_EnsureRemainingCapacity on context->common.buffer even though opus_decode writes decoded PCM into the caller-supplied out stream. A malicious RDP server that negotiates WAVE_FORMAT_OPUS with a client built with WITH_OPUS enabled and WITH_DSP_FFMPEG disabled can make libopus write a large decoded frame beyond the 4096-byte StreamPool_Take destination used by channels/rdpsnd/client/rdpsnd_main.c. This can corrupt the client heap, crash the client, and may permit code execution. This issue is fixed in version 3.28.0.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
60
EG Risk 60/100

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 (value × EchelonGraph’s weight)
Severity98% × 45%
The EG Score, 9.8 of 10.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.6%
EPSS %ILE
48th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 19, 2026

Last Modified

September 24, 2026

Advisory Details (4)

Auto-updated Oct 8, 2026
Patch available. Sources: github_commit, github_pr, github_release, github.
GitHub advisoryMentions a patch (unverified)

Heap buffer overflow in FreeRDP Opus audio decode (`freerdp_dsp_decode_opus` resizes the wrong stream) — server→client · Advisory · FreeRDP/FreeRDP · GitHub

Affected: 3.24.0) — that fix did not touch

https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-72j9-356v-88xq
GitHub release Patch Available

3.28.0

Patch available: FreeRDP/FreeRDP 3.28.0

https://github.com/FreeRDP/FreeRDP/releases/tag/3.28.0
GitHub pull request

Range checks

Fix merged in FreeRDP/FreeRDP PR #12993 on 2026-07-02 — awaiting tagged release

https://github.com/FreeRDP/FreeRDP/pull/12993
GitHub commit

commit 0ed1f95d3691 (FreeRDP/FreeRDP)

Fix landed in FreeRDP/FreeRDP commit 0ed1f95d3691 — awaiting tagged release

https://github.com/FreeRDP/FreeRDP/commit/0ed1f95d36913581cf31124f94eb5843d4263eae

Vendor Advisories for CVE-2026-63633(2)

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

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatfreerdp-2:3.10.3-3.el10_0.162026-09-17redhat
redhatfreerdp-2:3.10.3-12.el10_2.102026-08-31redhat

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 ... 3.32.0+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 ... 3.27.1+dfsg-1 (35 versions)
  • every version up to 3.28.0+dfsg-1: fixed in 3.28.0+dfsg-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 18× in last 7d / 125× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 198 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 98 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-14 01:49 UTCEG score recompute
  2. 2026-10-14 01:49 UTCVendor advisory
  3. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  4. 2026-10-12 22:02 UTCEG score recompute
  5. 2026-10-12 22:02 UTCVendor advisory
  6. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  7. 2026-10-12 15:49 UTCEG score recompute
  8. 2026-10-12 06:13 UTCVendor advisory
  9. 2026-10-11 19:33 UTCEG score recompute
  10. 2026-10-11 16:48 UTCEG score recompute
  11. 2026-10-11 14:10 UTCEG score recompute
  12. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  13. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  14. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  15. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  16. 2026-10-08 07:40 UTCEG score recompute
  17. 2026-10-08 07:40 UTCVendor advisory
  18. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  19. 2026-10-07 10:57 UTCVendor advisory
  20. 2026-10-07 06:37 UTCVendor advisory
  21. 2026-10-07 02:13 UTCVendor advisory
  22. 2026-10-06 21:21 UTCVendor advisory
  23. 2026-10-06 16:58 UTCEG score recompute
  24. 2026-10-06 16:58 UTCVendor advisory
  25. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.6% · 47th percentile
Show 75 more
  1. 2026-10-06 12:26 UTCVendor advisory
  2. 2026-10-06 07:57 UTCVendor advisory
  3. 2026-10-05 19:07 UTCEG score recompute
  4. 2026-10-05 19:07 UTCVendor advisory
  5. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  6. 2026-10-05 14:44 UTCVendor advisory
  7. 2026-10-05 10:25 UTCVendor advisory
  8. 2026-10-05 06:05 UTCVendor advisory
  9. 2026-10-05 01:45 UTCEG score recompute
  10. 2026-10-05 01:45 UTCVendor advisory
  11. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  12. 2026-10-04 21:24 UTCVendor advisory
  13. 2026-10-04 15:42 UTCVendor advisory
  14. 2026-10-04 11:20 UTCVendor advisory
  15. 2026-10-04 07:00 UTCVendor advisory
  16. 2026-10-04 02:41 UTCVendor advisory
  17. 2026-10-03 21:15 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 rescoreEPSS 0.6% · 47th percentile
  21. 2026-10-03 06:55 UTCVendor advisory
  22. 2026-10-03 02:11 UTCVendor advisory
  23. 2026-10-02 21:52 UTCEG score recompute
  24. 2026-10-02 21:52 UTCVendor advisory
  25. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  26. 2026-10-02 17:32 UTCVendor advisory
  27. 2026-10-02 12:57 UTCVendor advisory
  28. 2026-10-02 08:01 UTCVendor advisory
  29. 2026-10-02 03:41 UTCVendor advisory
  30. 2026-10-01 22:46 UTCEG score recompute
  31. 2026-10-01 22:46 UTCVendor advisory
  32. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  33. 2026-10-01 14:25 UTCVendor advisory
  34. 2026-10-01 10:02 UTCVendor advisory
  35. 2026-10-01 05:43 UTCVendor advisory
  36. 2026-10-01 01:23 UTCVendor advisory
  37. 2026-09-30 20:34 UTCEG score recompute
  38. 2026-09-30 20:34 UTCVendor advisory
  39. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  40. 2026-09-30 08:42 UTCEG score recompute
  41. 2026-09-30 08:42 UTCVendor advisory
  42. 2026-09-29 06:27 UTCVendor advisory
  43. 2026-09-29 02:07 UTCVendor advisory
  44. 2026-09-28 21:42 UTCEG score recompute
  45. 2026-09-28 21:42 UTCVendor advisory
  46. 2026-09-28 14:11 UTCEG score recompute
  47. 2026-09-28 14:11 UTCVendor advisory
  48. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  49. 2026-09-28 09:48 UTCVendor advisory
  50. 2026-09-28 05:28 UTCVendor advisory
  51. 2026-09-28 01:09 UTCVendor advisory
  52. 2026-09-27 20:49 UTCVendor advisory
  53. 2026-09-27 16:30 UTCEG score recompute
  54. 2026-09-27 16:30 UTCVendor advisory
  55. 2026-09-27 12:10 UTCVendor advisory
  56. 2026-09-27 06:54 UTCEG score recompute
  57. 2026-09-27 06:54 UTCVendor advisory
  58. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  59. 2026-09-25 09:30 UTCVendor advisory
  60. 2026-09-25 05:09 UTCVendor advisory
  61. 2026-09-25 00:50 UTCVendor advisory
  62. 2026-09-24 19:44 UTCVendor advisory
  63. 2026-09-24 15:14 UTCEG score recompute▲ 2.10
  64. 2026-09-24 15:14 UTCVendor advisory
  65. 2026-09-24 15:13 UTCNVD updateCVSS v3 → 9.8 · severity → CRITICAL
  66. 2026-09-24 07:53 UTCVendor advisory
  67. 2026-09-23 20:09 UTCEG score recompute
  68. 2026-09-23 20:09 UTCVendor advisory
  69. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  70. 2026-09-23 08:08 UTCVendor advisory
  71. 2026-09-22 20:24 UTCEG score recompute
  72. 2026-09-22 20:24 UTCVendor advisory
  73. 2026-09-22 08:41 UTCEG score recompute
  74. 2026-09-22 08:41 UTCVendor advisory
  75. 2026-09-21 20:57 UTCVendor advisory

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-63633?
CVE-2026-63633 is a critical-severity vulnerability; its CVE record was published on August 19, 2026. FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.28.0, freerdpdspdecodeopus in libfreerdp/codec/dsp.c calls StreamEnsureRemainingCapacity on context->common.buffer even though opusdecode writes decoded PCM into the caller-supplied out stream. A malicious RDP server that…
When was the CVE record for CVE-2026-63633 published?
The CVE record for CVE-2026-63633 was published on August 19, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 24, 2026; the record at its source may have been updated since.
Is CVE-2026-63633 actively exploited?
CVE-2026-63633 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (48th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-63633?
CVE-2026-63633 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-63633?
A fix for CVE-2026-63633 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-63633 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-63633

Explore →

Is Your Infrastructure Affected by CVE-2026-63633?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs