CVE-2026-54590

MEDIUMPre-NVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 68% 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
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.9Exploit: Elevated riskExposed: 0

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

AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Version 2.23.0 contains an incomplete fix for CVE-2026-45309 in SSHServerConfig._set_tokens that blocks /, , and .. before %u substitution in AuthorizedKeysFile but does not block a leading ~ or ${ENV}, allowing later expansion in _expand_val and Path(filename).expanduser() to escape the intended authorized-keys directory. This issue is fixed in version 2.23.1.

CVSS v3
5.9
EG Score
5.9(medium)
EG Risk
43(Track)
EG Risk 43/100SSVC: 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
Severity59% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
32%
KEV
Not listed

Published

July 8, 2026

Last Modified

July 10, 2026

Advisory Details (2)

Auto-updated Jul 8, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit.
github_commit

commit 3d515ba9ba0c (ronf/asyncssh)

Fix landed in ronf/asyncssh commit 3d515ba9ba0c — awaiting tagged release

https://github.com/ronf/asyncssh/commit/3d515ba9ba0cd9990d248bdf62bcf05d51261a88
github Patch Available🟡 PoC Available

Incomplete fix for CVE-2026-45309 — AuthorizedKeysFile %u still escapes the intended directory via a leading ~ (and weakly via ${ENV}) username substitution · Advisory · ronf/asyncssh · GitHub

Affected: v2.23.0, commit 2af2382) added a blocklist in

https://github.com/ronf/asyncssh/security/advisories/GHSA-qr67-gv47-xwwh

Vendor Advisories for CVE-2026-54590(1)

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

Affected Packages

(1 across 1 ecosystem)
Debian:14(1)
PackageVulnerable rangeFixed inDependents
python-asyncssh2.20.0-1 ... 2.23.0-1 (6 versions)——

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 49× 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. 2026-08-27 21:49 UTCEG score recompute
  2. 2026-08-27 14:25 UTCEPSS rescore
  3. 2026-08-26 14:46 UTCEPSS rescore
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  10. 2026-08-21 23:49 UTCEPSS rescore
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  1. 2026-08-12 14:05 UTCEG score recompute
  2. 2026-08-12 13:51 UTCEPSS rescore
  3. 2026-08-11 14:17 UTCEG score recompute
  4. 2026-08-11 00:00 UTCEPSS rescore
  5. 2026-08-09 14:51 UTCEG score recompute
  6. 2026-08-09 13:46 UTCEPSS rescore
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  8. 2026-08-08 15:09 UTCEG score recompute
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  10. 2026-08-06 13:47 UTCEPSS rescore
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  19. 2026-08-01 04:16 UTCEPSS rescore
  20. 2026-07-31 11:57 UTCEG score recompute
  21. 2026-07-30 16:28 UTCEPSS rescore
  22. 2026-07-30 12:14 UTCEG score recompute
  23. 2026-07-30 01:30 UTCEPSS rescore
  24. 2026-07-29 12:04 UTCEG score recompute
  25. 2026-07-28 15:37 UTCEPSS rescore
  26. 2026-07-28 12:21 UTCEG score recompute
  27. 2026-07-27 12:09 UTCEG score recompute
  28. 2026-07-26 14:54 UTCEPSS rescore
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  30. 2026-07-25 14:18 UTCEPSS rescore
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  32. 2026-07-23 14:18 UTCEPSS rescore
  33. 2026-07-23 03:19 UTCEG score recompute
  34. 2026-07-22 14:08 UTCEPSS rescore
  35. 2026-07-21 15:25 UTCEPSS rescore
  36. 2026-07-20 17:08 UTCEPSS rescore
  37. 2026-07-19 14:31 UTCEPSS rescore
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  39. 2026-07-19 02:29 UTCEPSS rescore
  40. 2026-07-18 10:04 UTCEPSS rescore
  41. 2026-07-16 17:03 UTCEPSS rescore
  42. 2026-07-15 16:57 UTCEPSS rescore
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  44. 2026-07-15 02:00 UTCEPSS rescore
  45. 2026-07-15 02:00 UTCEPSS rescore
  46. 2026-07-13 22:31 UTCEPSS rescore
  47. 2026-07-13 06:13 UTCEPSS rescore
  48. 2026-07-13 06:13 UTCEPSS rescore
  49. 2026-07-12 05:46 UTCEPSS rescore
  50. 2026-07-11 08:27 UTCEPSS rescore
  51. 2026-07-11 08:27 UTCEPSS rescore
  52. 2026-07-09 19:10 UTCEPSS rescore
  53. 2026-07-09 19:10 UTCEPSS rescore
  54. 2026-07-08 20:44 UTCEG score recompute
  55. 2026-07-08 20:44 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-54590?
CVE-2026-54590 is a medium vulnerability published on July 8, 2026. AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Version 2.23.0 contains an incomplete fix for CVE-2026-45309 in SSHServerConfig.settokens that blocks /, , and .. before %u substitution in…
When was CVE-2026-54590 disclosed?
CVE-2026-54590 was first published in the National Vulnerability Database on July 8, 2026, with the most recent update on July 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-54590 actively exploited?
CVE-2026-54590 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 67.7% of all scored CVEs.
What is the CVSS score of CVE-2026-54590?
CVE-2026-54590 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-54590?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-54590, 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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