CVE-2021-31800

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 39.8%, top 3% 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, nvd
Elevated
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 19%CVSS: 9.8Exploit: NoneExposed: 0

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

Multiple path traversal vulnerabilities exist in smbserver.py in Impacket through 0.9.22. An attacker that connects to a running smbserver instance can list and write to arbitrary files via ../ directory traversal. This could potentially be abused to achieve arbitrary code execution by replacing /etc/shadow or an SSH authorized key.

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
97.0%
KEV
Not listed

Published

May 5, 2021

Last Modified

November 21, 2024

Advisory Details (9)

Auto-updated Jun 10, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic

impacket/impacket/smbserver.py at cb6d43a677c338db930bc4e9161620832c1ec624 · fortra/impacket · GitHub

https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L2008
generic

[SECURITY] Fedora 34 Update: python-impacket-0.9.22-3.fc34 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UF56LYB27LHEIFJTFHU3M75NMNNK2SCG/
generic

[SECURITY] Fedora 32 Update: python-impacket-0.9.22-3.fc32 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KRV2C5DATXBHG6TF6CEEX54KZ75THQS3/
generic

[SECURITY] Fedora 33 Update: python-impacket-0.9.22-3.fc33 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IPXDPWCAPVX3UWYZ3N2T5OLBSBBUHJP6/
generic

Releases · fortra/impacket · GitHub

https://github.com/SecureAuthCorp/impacket/releases
github_commit

commit 49c643bf6662 (SecureAuthCorp/impacket)

Fix landed in SecureAuthCorp/impacket commit 49c643bf6662 — awaiting tagged release

https://github.com/SecureAuthCorp/impacket/commit/49c643bf66620646884ed141c94e5fdd85bcdd2f
generic

impacket/impacket/smbserver.py at cb6d43a677c338db930bc4e9161620832c1ec624 · fortra/impacket · GitHub

https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L876
generic

impacket/impacket/smbserver.py at cb6d43a677c338db930bc4e9161620832c1ec624 · fortra/impacket · GitHub

https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L3485
generic

impacket/impacket/smbserver.py at cb6d43a677c338db930bc4e9161620832c1ec624 · fortra/impacket · GitHub

https://github.com/SecureAuthCorp/impacket/blob/cb6d43a677c338db930bc4e9161620832c1ec624/impacket/smbserver.py#L2958

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
impacket0.9.10 ... 0.9.22 (12 versions)0.9.23—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 38× 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. 2026-07-13 22:27 UTCEPSS rescore
  2. 2026-07-13 06:10 UTCEPSS rescore
  3. 2026-07-12 05:44 UTCEPSS rescore
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  5. 2026-07-11 08:25 UTCEPSS rescore
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  7. 2026-07-09 19:07 UTCEPSS rescore
  8. 2026-07-08 15:12 UTCEPSS rescore
  9. 2026-07-07 13:43 UTCEPSS rescore
  10. 2026-07-06 16:25 UTCEPSS rescore
  11. 2026-07-06 02:21 UTCEPSS rescore
  12. 2026-07-05 02:28 UTCEPSS rescore
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  14. 2026-07-01 15:04 UTCEPSS rescore
  15. 2026-07-01 04:18 UTCOSV refresh
  16. 2026-06-30 23:20 UTCEPSS rescore
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  18. 2026-06-28 14:05 UTCEPSS rescore
  19. 2026-06-28 04:54 UTCEPSS rescore
  20. 2026-06-28 04:54 UTCEPSS rescore
  21. 2026-06-27 03:06 UTCEPSS rescore
  22. 2026-06-25 13:48 UTCEPSS rescore
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  24. 2026-06-24 14:03 UTCEPSS rescore
  25. 2026-06-24 14:03 UTCEPSS rescore
Show 49 more
  1. 2026-06-23 21:31 UTCEPSS rescore
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  3. 2026-06-22 14:24 UTCEPSS rescore
  4. 2026-06-22 14:24 UTCEPSS rescore
  5. 2026-06-21 14:55 UTCEPSS rescore
  6. 2026-06-21 01:58 UTCEPSS rescore
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  8. 2026-06-18 17:51 UTCEPSS rescore
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  10. 2026-06-17 17:51 UTCEPSS rescore
  11. 2026-06-16 17:51 UTCEPSS rescore
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  15. 2026-06-13 22:58 UTCEPSS rescore
  16. 2026-06-13 22:58 UTCEPSS rescore
  17. 2026-06-13 07:13 UTCOSV refresh
  18. 2026-06-12 23:10 UTCEPSS rescore
  19. 2026-06-12 23:10 UTCEPSS rescore
  20. 2026-06-11 13:58 UTCEPSS rescore
  21. 2026-06-10 22:16 UTCEPSS rescore
  22. 2026-06-10 13:20 UTCEPSS rescore
  23. 2026-06-08 14:15 UTCEPSS rescore
  24. 2026-06-08 14:15 UTCEPSS rescore
  25. 2026-06-06 13:46 UTCEPSS rescore
  26. 2026-06-06 13:46 UTCEPSS rescore
  27. 2026-06-06 13:46 UTCEPSS rescore
  28. 2026-06-05 22:45 UTCEPSS rescore
  29. 2026-06-05 06:09 UTCEPSS rescore
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  31. 2026-06-04 13:10 UTCEPSS rescore
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  35. 2026-06-01 13:50 UTCEPSS rescore
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  37. 2026-05-31 22:29 UTCEPSS rescore
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  39. 2026-05-31 00:15 UTCEPSS rescore
  40. 2026-05-31 00:15 UTCEPSS rescore
  41. 2026-05-29 13:42 UTCEPSS rescore
  42. 2026-05-28 13:43 UTCEPSS rescore
  43. 2026-05-28 13:43 UTCEPSS rescore
  44. 2026-05-27 13:39 UTCEPSS rescore
  45. 2026-05-27 13:39 UTCEPSS rescore
  46. 2026-05-26 17:09 UTCEG score recompute
  47. 2026-05-26 13:42 UTCEPSS rescore
  48. 2026-05-26 07:17 UTCEPSS rescore
  49. 2026-05-26 07:17 UTCEPSS rescore

Publicly available exploits

(2 references)

Working exploit code is in the public domain (2 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCLouzogh/CVE-2021-31800
    First seen Sep 2, 2022

    CVE-2021-31800 POC

    Open source ↗
  • GitHub PoCp0dalirius/CVE-2021-31800-Impacket-SMB-Server-Arbitrary-file-read-write
    First seen Aug 28, 2022

    A path traversal in smbserver.py allows an attacker to read/write arbitrary files on the server.

    Open source ↗

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-31800?
CVE-2021-31800 is a critical vulnerability published on May 5, 2021. Multiple path traversal vulnerabilities exist in smbserver.py in Impacket through 0.9.22. An attacker that connects to a running smbserver instance can list and write to arbitrary files via ../ directory traversal. This could potentially be abused to achieve arbitrary code execution by replacing…
When was CVE-2021-31800 disclosed?
CVE-2021-31800 was first published in the National Vulnerability Database on May 5, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-31800 actively exploited?
CVE-2021-31800 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 97.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-31800?
CVE-2021-31800 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2021-31800?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-31800, 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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