CVE-2026-63633

HIGHPre-NVD 7.77.7—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 62% 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
Elevated
7.7EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.7Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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
7.7
EG Score
7.7(medium)
EG Risk
51(Track*)
EG Risk 51/100SSVC: 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
Severity77% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
0%
EPSS %ILE
38%
KEV
Not listed

Published

August 19, 2026

Last Modified

August 27, 2026

Advisory Details (4)

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

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_pr

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 20× 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. 2026-08-30 01:22 UTCEPSS rescore
  2. 2026-08-29 07:23 UTCEG score recompute
  3. 2026-08-28 21:42 UTCEPSS rescore
  4. 2026-08-27 17:24 UTCEG score recompute
  5. 2026-08-27 14:25 UTCEPSS rescore
  6. 2026-08-27 01:30 UTCEG score recompute
  7. 2026-08-26 14:46 UTCEPSS rescore
  8. 2026-08-25 14:19 UTCEG score recompute
  9. 2026-08-25 13:49 UTCEPSS rescore
  10. 2026-08-24 14:51 UTCEG score recompute
  11. 2026-08-23 03:39 UTCEG score recompute
  12. 2026-08-23 00:19 UTCEPSS rescore
  13. 2026-08-22 04:12 UTCEG score recompute
  14. 2026-08-21 23:49 UTCEPSS rescore
  15. 2026-08-21 04:36 UTCEG score recompute
  16. 2026-08-21 04:02 UTCEG score recompute
  17. 2026-08-20 22:55 UTCEPSS rescore
  18. 2026-08-19 18:18 UTCEG score recompute
  19. 2026-08-19 18:13 UTCEG score recompute
  20. 2026-08-19 18:12 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-63633?
CVE-2026-63633 is a high vulnerability 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 CVE-2026-63633 disclosed?
CVE-2026-63633 was first published in the National Vulnerability Database on August 19, 2026, with the most recent update on August 27, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63633 actively exploited?
CVE-2026-63633 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 62.0% of all scored CVEs.
What is the CVSS score of CVE-2026-63633?
CVE-2026-63633 has a CVSS v3 base score of 7.7 (NVD).
How do I remediate CVE-2026-63633?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63633, 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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