CVE-2026-64620

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-20. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: None knownExposed: 0

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

FreeRDP before 3.28.0 (affected <=3.27.1) contains a heap-based buffer overflow in crypto_rsa_common() (libfreerdp/crypto/crypto.c). The function writes the modular-exponentiation result into the caller's output buffer via BN_bn2bin() and only afterward checks output_length > out_length, so out-of-bounds bytes are written before the bounds check. On the server side, when a client selects RDP Standard Security, the encrypted client random is decrypted into a fixed 32-byte buffer. Because the server publishes its RSA public key, an unauthenticated attacker can forge a ciphertext whose decrypted value is up to the full modulus length (e.g. 256 bytes for RSA-2048), overflowing the 32-byte heap buffer by up to ~224 attacker-controlled bytes pre-authentication, resulting in denial of service.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
59(Track)
EG Risk 59/100SSVC: 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
Severity98% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
44%
KEV
Not listed

Published

July 20, 2026

Last Modified

July 23, 2026

Advisory Details (3)

Auto-updated Jul 25, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github.
generic

FreeRDP before 3.28.0 Heap Buffer Overflow via crypto_rsa_common | Advisories | VulnCheck

https://www.vulncheck.com/advisories/freerdp-before-heap-buffer-overflow-via-crypto-rsa-common
github Patch Available🟡 PoC Available

Pre-auth server heap overflow: `crypto_rsa_common` writes the decrypted client random with `BN_bn2bin` before checking the 32-byte output buffer · Advisory · FreeRDP/FreeRDP · GitHub

https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-pjqx-v446-x7fc
github_commit

commit 1f7a716d39b5 (FreeRDP/FreeRDP)

Fix landed in FreeRDP/FreeRDP commit 1f7a716d39b5 — awaiting tagged release

https://github.com/FreeRDP/FreeRDP/commit/1f7a716d39b5605bb8a83b0c3c97a6ce386609ef

Vendor Advisories for CVE-2026-64620(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 28× in last 7d / 28× 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. 2026-07-27 02:56 UTCGHSA enrichment
  2. 2026-07-26 22:55 UTCGHSA enrichment
  3. 2026-07-26 18:56 UTCEG score recompute
  4. 2026-07-26 18:55 UTCGHSA enrichment
  5. 2026-07-26 14:54 UTCEPSS rescore
  6. 2026-07-26 14:54 UTCEPSS rescore
  7. 2026-07-26 14:52 UTCGHSA enrichment
  8. 2026-07-26 10:49 UTCEG score recompute
  9. 2026-07-26 10:49 UTCGHSA enrichment
  10. 2026-07-26 04:30 UTCEG score recompute
  11. 2026-07-26 04:30 UTCGHSA enrichment
  12. 2026-07-25 14:18 UTCEPSS rescore
  13. 2026-07-25 14:18 UTCEPSS rescore
  14. 2026-07-24 14:18 UTCEPSS rescore
  15. 2026-07-24 14:18 UTCEPSS rescore
  16. 2026-07-23 14:18 UTCEPSS rescore
  17. 2026-07-23 14:18 UTCEPSS rescore
  18. 2026-07-23 03:22 UTCEG score recompute
  19. 2026-07-22 23:41 UTCEG score recompute
  20. 2026-07-22 23:41 UTCGHSA enrichment
  21. 2026-07-22 14:08 UTCEPSS rescore
  22. 2026-07-22 14:08 UTCEPSS rescore
  23. 2026-07-21 15:25 UTCEPSS rescore
  24. 2026-07-21 15:25 UTCEPSS rescore
  25. 2026-07-20 12:37 UTCEG score recompute
Show 3 more
  1. 2026-07-20 12:37 UTCGHSA enrichment
  2. 2026-07-20 12:18 UTCEG score recompute
  3. 2026-07-20 12:17 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-64620?
CVE-2026-64620 is a critical vulnerability published on July 20, 2026. FreeRDP before 3.28.0 (affected <=3.27.1) contains a heap-based buffer overflow in cryptorsacommon() (libfreerdp/crypto/crypto.c). The function writes the modular-exponentiation result into the caller's output buffer via BNbn2bin() and only afterward checks outputlength > out_length, so…
When was CVE-2026-64620 disclosed?
CVE-2026-64620 was first published in the National Vulnerability Database on July 20, 2026, with the most recent update on July 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-64620 actively exploited?
CVE-2026-64620 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 55.9% of all scored CVEs.
What is the CVSS score of CVE-2026-64620?
CVE-2026-64620 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-64620?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-64620, 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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