CVE-2026-67303

MEDIUMPre-NVD 4.34.3—
EchelonGraph scoreHIGH confidence

Score 4.3 from GitHub Security Advisory published 2026-08-01. a secondary CVSS source baseline 4.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this weekElevated
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.3Exploit: Elevated riskExposed: 0

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

FreeRDP before 3.29.0 contains a reachable assertion (WINPR_ASSERT(OutputBufferLength == BytesReturned)) in serial_process_irp_device_control() in channels/serial/client/serial_main.c. When serial device redirection is enabled and a server-controlled IRP_MJ_DEVICE_CONTROL request specifies an unsupported IOCTL with a non-zero OutputBufferLength, CommDeviceIoControl() can fail with BytesReturned = 0, causing the mismatch to trigger the assertion and abort the client process (denial of service).

CVSS v3
4.3
EG Score
4.3(high)
EG Risk
35(Track)
EG Risk 35/100SSVC: 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
Severity43% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
16%
KEV
Not listed

Published

August 1, 2026

Last Modified

August 3, 2026

Advisory Details (4)

Auto-updated Aug 1, 2026
Patch available. Sources: github, github_commit.
generic

FreeRDP before 3.29.0 Denial of Service via serial DeviceControl | Advisories | VulnCheck

https://www.vulncheck.com/advisories/freerdp-before-denial-of-service-via-serial-devicecontrol
github_commit

commit 5370fb26fbf0 (FreeRDP/FreeRDP)

Fix landed in FreeRDP/FreeRDP commit 5370fb26fbf0 — awaiting tagged release

https://github.com/FreeRDP/FreeRDP/commit/5370fb26fbf034ecd11d3026b6ad639b5fff493f
github_commit

commit 1cc783d4c78b (FreeRDP/FreeRDP)

Fix landed in FreeRDP/FreeRDP commit 1cc783d4c78b — awaiting tagged release

https://github.com/FreeRDP/FreeRDP/commit/1cc783d4c78bd2f66d3a8582dfe70a663d141444
github Patch Available

FreeRDP serial DeviceControl reachable assertion DoS · Advisory · FreeRDP/FreeRDP · GitHub

https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-pfxq-3qmw-8vjx

Vendor Advisories for CVE-2026-67303(1)

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

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
freerdp22.10.0+dfsg1-1 ... 2.9.0+dfsg1-1~bpo11+1 (32 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
freerdp22.10.0+dfsg1-1 ... 2.11.7+dfsg1-6~deb12u1 (13 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
freerdp33.15.0+dfsg-2.1 ... 3.30.0+dfsg-1~bpo13+1 (43 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
freerdp33.15.0+dfsg-2.1 ... 3.28.0+dfsg-2 (37 versions)3.29.0+dfsg-1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 19× in last 7d / 60× 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. 2026-08-20 22:56 UTCEPSS rescore
  2. 2026-08-20 19:34 UTCGHSA enrichment
  3. 2026-08-19 20:57 UTCEG score recompute
  4. 2026-08-19 20:57 UTCGHSA enrichment
  5. 2026-08-19 17:04 UTCEPSS rescore
  6. 2026-08-18 22:15 UTCEG score recompute
  7. 2026-08-18 22:15 UTCGHSA enrichment
  8. 2026-08-18 13:48 UTCEPSS rescore
  9. 2026-08-17 23:38 UTCEG score recompute
  10. 2026-08-17 23:38 UTCGHSA enrichment
  11. 2026-08-17 13:47 UTCEPSS rescore
  12. 2026-08-17 01:01 UTCEG score recompute
  13. 2026-08-17 01:01 UTCGHSA enrichment
  14. 2026-08-16 14:56 UTCEPSS rescore
  15. 2026-08-16 02:24 UTCEG score recompute
  16. 2026-08-16 02:24 UTCGHSA enrichment
  17. 2026-08-15 03:47 UTCEG score recompute
  18. 2026-08-15 03:47 UTCGHSA enrichment
  19. 2026-08-15 01:30 UTCEPSS rescore
  20. 2026-08-14 05:09 UTCEG score recompute
  21. 2026-08-14 05:09 UTCGHSA enrichment
  22. 2026-08-13 22:00 UTCEPSS rescore
  23. 2026-08-13 06:32 UTCEG score recompute
  24. 2026-08-13 06:32 UTCGHSA enrichment
  25. 2026-08-12 13:51 UTCEPSS rescore
Show 35 more
  1. 2026-08-12 07:55 UTCEG score recompute
  2. 2026-08-12 07:55 UTCGHSA enrichment
  3. 2026-08-11 09:18 UTCEG score recompute
  4. 2026-08-11 09:18 UTCGHSA enrichment
  5. 2026-08-11 00:00 UTCEPSS rescore
  6. 2026-08-10 10:41 UTCEG score recompute
  7. 2026-08-10 10:40 UTCGHSA enrichment
  8. 2026-08-09 13:47 UTCEPSS rescore
  9. 2026-08-09 12:03 UTCEG score recompute
  10. 2026-08-09 12:03 UTCGHSA enrichment
  11. 2026-08-08 16:37 UTCEPSS rescore
  12. 2026-08-08 13:26 UTCEG score recompute
  13. 2026-08-08 13:26 UTCGHSA enrichment
  14. 2026-08-07 14:48 UTCGHSA enrichment
  15. 2026-08-06 16:12 UTCEG score recompute
  16. 2026-08-06 16:12 UTCGHSA enrichment
  17. 2026-08-06 13:47 UTCEPSS rescore
  18. 2026-08-05 19:17 UTCEPSS rescore
  19. 2026-08-05 19:17 UTCEPSS rescore
  20. 2026-08-05 17:34 UTCGHSA enrichment
  21. 2026-08-04 18:57 UTCEG score recompute
  22. 2026-08-04 18:57 UTCGHSA enrichment
  23. 2026-08-04 15:10 UTCEPSS rescore
  24. 2026-08-04 10:39 UTCEPSS rescore
  25. 2026-08-03 20:20 UTCEG score recompute
  26. 2026-08-03 20:20 UTCGHSA enrichment
  27. 2026-08-03 20:14 UTCEG score recompute
  28. 2026-08-03 20:14 UTCGHSA enrichment
  29. 2026-08-03 10:36 UTCEPSS rescore
  30. 2026-08-03 10:34 UTCGHSA enrichment
  31. 2026-08-02 11:55 UTCEG score recompute
  32. 2026-08-02 11:55 UTCGHSA enrichment
  33. 2026-08-01 13:18 UTCEG score recompute
  34. 2026-08-01 12:43 UTCEG score recompute
  35. 2026-08-01 12:42 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-67303?
CVE-2026-67303 is a medium vulnerability published on August 1, 2026. FreeRDP before 3.29.0 contains a reachable assertion (WINPRASSERT(OutputBufferLength == BytesReturned)) in serialprocessirpdevicecontrol() in channels/serial/client/serialmain.c. When serial device redirection is enabled and a server-controlled IRPMJDEVICE_CONTROL request specifies an unsupported…
When was CVE-2026-67303 disclosed?
CVE-2026-67303 was first published in the National Vulnerability Database on August 1, 2026, with the most recent update on August 3, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-67303 actively exploited?
CVE-2026-67303 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 83.5% of all scored CVEs.
What is the CVSS score of CVE-2026-67303?
CVE-2026-67303 has a CVSS v3 base score of 4.3 (NVD).
How do I remediate CVE-2026-67303?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-67303, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-67303

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