CVE-2021-41773

CRITICALNVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score elevated to 9.8 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 9.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 4 sources updated this weekExploited in the wild
9.8EG
EchelonGraph verdictMitigate nowTreat as an emergency — this is being exploited.
  • 1 internet-facing service (distinct ip:port) on record running an affected version — derived from Shodan data (© Shodan); a patched service can stay counted while its port stays open
  • Actively exploited in the wild (CISA-KEV)
  • Linked to ransomware campaigns
CISA-KEV: ExploitedEPSS PROB: 100%CVSS: 9.8Exploit: cisa kev · ssvc active · kev ransomware · Metasploit · Exploit-DB (verified) · epss top5pct · epss high · public exploitExposed services: 1

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

A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49. An attacker could use a path traversal attack to map URLs to files outside the directories configured by Alias-like directives. If files outside of these directories are not protected by the usual default configuration "require all denied", these requests can succeed. If CGI scripts are also enabled for these aliased pathes, this could allow for remote code execution. This issue is known to be exploited in the wild. This issue only affects Apache 2.4.49 and not earlier versions. The fix in Apache HTTP Server 2.4.50 was found to be incomplete, see CVE-2021-42013.

Internet exposure · derived from Shodan data

1 internet-facing service (distinct ip:port) on record running a version that maps to CVE-2021-41773, in our KEV-Exposure radar’s Shodan-derived sample.

across 1 countries (United States)top: http_server🔒 ransomware-linked
See the KEV-Exposure radar →Derived from Shodan data. Shodan data is owned by Shodan, which holds its copyright (© Shodan). EchelonGraph claims no ownership of it or copyright in it. Aggregate, host-redacted.

How it counts: every 12 hours, when Shodan query credits allow, the radar runs one Shodan query per tracked product, reads up to 100 ip:port services per query, and keeps a service when its banner version matches a CISA-KEV or high-EPSS CVE; a service is dropped when neither a search nor a Shodan InternetDB port re-check has refreshed it for 21 days. A re-check that finds the port still listed by Shodan InternetDB refreshes the service without re-reading the banner, so a patched service can stay counted while its port stays open. A count is a banner-version inference over a sample, not an exploit test and not an internet-wide census, and the unit is a service, not a machine: a machine answering on two ports counts twice.

CVSS v3
9.8
EG Score
9.8CRITICALhigh confidence
EG Risk
99
EG Risk 99/100CISA SSVC

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%
Exploitation100% × 40%
Automatability100% × 15%
CISA SSVC: Attend at low mission impact; Act at medium or high.
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation sooner than your standard update timelines at low mission impact and as soon as possible at medium or high, and watch the vendor's advisory for the fix.
EPSS PROB
100%
EPSS %ILE
99th
KEV
⚠ Exploited

CISA SSVCAttend at low mission impact; Act at medium or high.

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation sooner than your standard update timelines at low mission impact and as soon as possible at medium or high, and watch the vendor's advisory for the fix.

Exploitation active (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

October 5, 2021

Last Modified

February 17, 2026

Advisory Details (10)

Auto-updated Oct 1, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic

oss-security - Re: CVE-2021-42013: Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)

http://www.openwall.com/lists/oss-security/2021/10/08/3
generic

oss-security - Re: CVE-2021-42013: Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)

http://www.openwall.com/lists/oss-security/2021/10/08/2
generic

oss-security - Re: CVE-2021-42013: Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)

http://www.openwall.com/lists/oss-security/2021/10/08/1
generic

oss-security - CVE-2021-42013: Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)

http://www.openwall.com/lists/oss-security/2021/10/07/6
generic🔴 Active Exploitation

oss-security - RE: CVE-2021-41773: Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49

http://www.openwall.com/lists/oss-security/2021/10/07/1
generic🔴 Active Exploitation

oss-security - CVE-2021-41773: Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49

http://www.openwall.com/lists/oss-security/2021/10/05/2
generic

Packet Storm - Human Validation

http://packetstormsecurity.com/files/164941/Apache-HTTP-Server-2.4.50-Remote-Code-Execution.html
generic

Packet Storm - Human Validation

http://packetstormsecurity.com/files/164629/Apache-2.4.49-2.4.50-Traversal-Remote-Code-Execution.html
generic

Packet Storm - Human Validation

http://packetstormsecurity.com/files/164418/Apache-HTTP-Server-2.4.49-Path-Traversal.html
generic

Packet Storm - Human Validation

http://packetstormsecurity.com/files/164418/Apache-HTTP-Server-2.4.49-Path-Traversal-Remote-Code-Execution.html

Vendor Advisories for CVE-2021-41773(1)

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

Affected Packages

(17 across 17 ecosystems)
Alpine:v3.11(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.12(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.13(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.14(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.15(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.16(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.17(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.18(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.19(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.20(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.21(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.22(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.23(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Alpine:v3.24(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-r0—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.50-1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 91× in last 7d / 396× 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.

Showing the most recent 100 of 1,606 total refreshes for this CVE.

  1. 2026-10-04 12:10 UTCVendor advisory
  2. 2026-10-04 12:10 UTCGHSA enrichment
  3. 2026-10-04 08:29 UTCVendor advisory
  4. 2026-10-04 08:29 UTCGHSA enrichment
  5. 2026-10-04 04:47 UTCVendor advisory
  6. 2026-10-04 04:47 UTCGHSA enrichment
  7. 2026-10-04 01:06 UTCVendor advisory
  8. 2026-10-04 01:06 UTCGHSA enrichment
  9. 2026-10-03 21:25 UTCVendor advisory
  10. 2026-10-03 21:25 UTCGHSA enrichment
  11. 2026-10-03 17:43 UTCVendor advisory
  12. 2026-10-03 17:43 UTCGHSA enrichment
  13. 2026-10-03 14:02 UTCVendor advisory
  14. 2026-10-03 14:02 UTCGHSA enrichment
  15. 2026-10-03 10:21 UTCVendor advisory
  16. 2026-10-03 10:21 UTCGHSA enrichment
  17. 2026-10-03 06:40 UTCVendor advisory
  18. 2026-10-03 06:40 UTCGHSA enrichment
  19. 2026-10-03 02:58 UTCVendor advisory
  20. 2026-10-03 02:58 UTCGHSA enrichment
  21. 2026-10-02 23:17 UTCVendor advisory
  22. 2026-10-02 23:16 UTCGHSA enrichment
  23. 2026-10-02 19:32 UTCVendor advisory
  24. 2026-10-02 19:32 UTCGHSA enrichment
  25. 2026-10-02 15:50 UTCVendor advisory
Show 75 more
  1. 2026-10-02 15:50 UTCGHSA enrichment
  2. 2026-10-02 12:09 UTCVendor advisory
  3. 2026-10-02 12:09 UTCGHSA enrichment
  4. 2026-10-02 08:25 UTCVendor advisory
  5. 2026-10-02 08:25 UTCGHSA enrichment
  6. 2026-10-02 04:43 UTCVendor advisory
  7. 2026-10-02 04:43 UTCGHSA enrichment
  8. 2026-10-02 01:02 UTCVendor advisory
  9. 2026-10-02 01:02 UTCGHSA enrichment
  10. 2026-10-01 21:18 UTCVendor advisory
  11. 2026-10-01 21:18 UTCGHSA enrichment
  12. 2026-10-01 17:37 UTCVendor advisory
  13. 2026-10-01 17:36 UTCGHSA enrichment
  14. 2026-10-01 13:52 UTCVendor advisory
  15. 2026-10-01 13:52 UTCGHSA enrichment
  16. 2026-10-01 10:11 UTCVendor advisory
  17. 2026-10-01 10:11 UTCGHSA enrichment
  18. 2026-10-01 06:30 UTCVendor advisory
  19. 2026-10-01 06:30 UTCGHSA enrichment
  20. 2026-10-01 02:49 UTCVendor advisory
  21. 2026-10-01 02:49 UTCGHSA enrichment
  22. 2026-09-30 23:07 UTCVendor advisory
  23. 2026-09-30 23:07 UTCGHSA enrichment
  24. 2026-09-30 19:22 UTCGHSA enrichment
  25. 2026-09-30 15:41 UTCVendor advisory
  26. 2026-09-30 15:41 UTCGHSA enrichment
  27. 2026-09-30 11:59 UTCVendor advisory
  28. 2026-09-30 11:59 UTCGHSA enrichment
  29. 2026-09-30 08:18 UTCVendor advisory
  30. 2026-09-30 08:18 UTCGHSA enrichment
  31. 2026-09-30 04:36 UTCVendor advisory
  32. 2026-09-30 04:36 UTCGHSA enrichment
  33. 2026-09-30 00:53 UTCVendor advisory
  34. 2026-09-30 00:53 UTCGHSA enrichment
  35. 2026-09-29 21:12 UTCVendor advisory
  36. 2026-09-29 21:11 UTCGHSA enrichment
  37. 2026-09-29 17:29 UTCVendor advisory
  38. 2026-09-29 17:28 UTCGHSA enrichment
  39. 2026-09-29 13:43 UTCVendor advisory
  40. 2026-09-29 13:43 UTCGHSA enrichment
  41. 2026-09-29 10:02 UTCVendor advisory
  42. 2026-09-29 10:01 UTCGHSA enrichment
  43. 2026-09-29 06:19 UTCVendor advisory
  44. 2026-09-29 06:19 UTCGHSA enrichment
  45. 2026-09-29 02:38 UTCVendor advisory
  46. 2026-09-29 02:38 UTCGHSA enrichment
  47. 2026-09-28 22:56 UTCEG score recompute
  48. 2026-09-28 22:56 UTCVendor advisory
  49. 2026-09-28 22:55 UTCGHSA enrichment
  50. 2026-09-28 19:13 UTCVendor advisory
  51. 2026-09-28 19:13 UTCGHSA enrichment
  52. 2026-09-28 15:29 UTCVendor advisory
  53. 2026-09-28 15:29 UTCGHSA enrichment
  54. 2026-09-28 11:47 UTCVendor advisory
  55. 2026-09-28 11:47 UTCGHSA enrichment
  56. 2026-09-28 08:06 UTCVendor advisory
  57. 2026-09-28 08:06 UTCGHSA enrichment
  58. 2026-09-28 04:25 UTCVendor advisory
  59. 2026-09-28 04:25 UTCGHSA enrichment
  60. 2026-09-28 00:43 UTCVendor advisory
  61. 2026-09-28 00:43 UTCGHSA enrichment
  62. 2026-09-27 21:51 UTCCISA KEV update
  63. 2026-09-27 21:01 UTCVendor advisory
  64. 2026-09-27 21:01 UTCGHSA enrichment
  65. 2026-09-27 17:20 UTCVendor advisory
  66. 2026-09-27 17:20 UTCGHSA enrichment
  67. 2026-09-27 13:36 UTCVendor advisory
  68. 2026-09-27 13:36 UTCGHSA enrichment
  69. 2026-09-27 09:53 UTCVendor advisory
  70. 2026-09-27 09:53 UTCGHSA enrichment
  71. 2026-09-27 06:12 UTCVendor advisory
  72. 2026-09-27 06:11 UTCGHSA enrichment
  73. 2026-09-27 02:31 UTCVendor advisory
  74. 2026-09-27 02:31 UTCGHSA enrichment
  75. 2026-09-26 22:49 UTCVendor advisory

Publicly available exploits

(10 references)

Working exploit code is in the public domain (2 Metasploit modules) (6 GitHub PoCs) (2 Exploit-DB entries). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-50512✓ verified
    First seen Nov 11, 2021

    Apache HTTP Server 2.4.50 - Remote Code Execution (RCE) (3)

    Open source ↗
  • Exploit-DBEDB-50383✓ verified
    First seen Oct 6, 2021

    Apache HTTP Server 2.4.49 - Path Traversal & Remote Code Execution (RCE)

    Open source ↗
  • Metasploitauxiliary/scanner/http/apache_normalize_path✓ verified
    First seen May 10, 2021

    Apache 2.4.49/2.4.50 Traversal RCE scanner

    Open source ↗
  • Metasploitexploit/multi/http/apache_normalize_path_rce✓ verified
    First seen May 10, 2021

    Apache 2.4.49/2.4.50 Traversal RCE

    Open source ↗
  • GitHub PoCthehackersbrain/CVE-2021-41773
    First seen Mar 12, 2022

    Apache2 2.4.49 - LFI & RCE Exploit - CVE-2021-41773

    Open source ↗
  • GitHub PoCMrCl0wnLab/SimplesApachePathTraversal
    First seen Oct 13, 2021

    Tool check: CVE-2021-41773, CVE-2021-42013, CVE-2020-17519

    Open source ↗
  • GitHub PoCim-hanzou/apachrot
    First seen Oct 9, 2021

    Apache (Linux) CVE-2021-41773/2021-42013 Mass Vulnerability Checker

    Open source ↗
  • GitHub PoCinbug-team/CVE-2021-41773_CVE-2021-42013
    First seen Oct 9, 2021

    CVE-2021-41773 CVE-2021-42013漏洞批量检测工具

    Open source ↗
  • GitHub PoCHightechSec/scarce-apache2
    First seen Oct 7, 2021

    A framework for bug hunting or pentesting targeting websites that have CVE-2021-41773 Vulnerability in public

    Open source ↗
  • GitHub PoCjustakazh/mass_cve-2021-41773
    First seen Oct 7, 2021

    MASS CVE-2021-41773

    Open source ↗

Related CVEs(same product + same CWE)

Frequently asked(6)

What is CVE-2021-41773?
CVE-2021-41773 is a critical vulnerability published on October 5, 2021. A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49. An attacker could use a path traversal attack to map URLs to files outside the directories configured by Alias-like directives. If files outside of these directories are not protected by the usual default…
When was CVE-2021-41773 disclosed?
CVE-2021-41773 was first published on October 5, 2021, with the most recent update on February 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-41773 actively exploited?
Yes. CISA added CVE-2021-41773 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting Apache HTTP Server. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate attention. No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation, and watch the vendor's advisory for the fix.
What is the CVSS score of CVE-2021-41773?
CVE-2021-41773 has a CVSS v3 base score of 9.8 (NVD).
Which products are affected by CVE-2021-41773?
CVE-2021-41773 affects Apache HTTP Server. The affected packages EchelonGraph has on record, with version ranges, are listed in the Affected Packages section of this page.
How do I remediate CVE-2021-41773?
No fix for CVE-2021-41773 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2021-41773 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-41773

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