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TI-2021-18417 Aliases CVE-2021-41773GHSA-29h7-gr57-5f8r

Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49

Priority CRITICAL 100Exploited in the wildCWE-22Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation Active In CISA KEV since 2021-11-03CISA due date 2021-11-17Known ransomware use
EPSS 0.99992 99th percentileScored 2026-11-07
Public exploit Yes 6 exploit referencesTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Active
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ApacheApache HTTP ServerApache HTTP Server 2.4 2.4.49—No fix listedCNA
  • Apache HTTP Server VendorApache Affected Apache HTTP Server 2.4 2.4.49 Fixed in — No fix listed CNA

CPE configurations NVD · 7

CPEVersionsRoleVendor
cpe:2.3:a:apache:http_server:2.4.49:*:*:*:*:*:*:*2.4.49VulnerableApache
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*34VulnerableFedoraproject
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*35VulnerableFedoraproject
cpe:2.3:a:oracle:instantis_enterprisetrack:17.1:*:*:*:*:*:*:*17.1VulnerableOracle
cpe:2.3:a:oracle:instantis_enterprisetrack:17.2:*:*:*:*:*:*:*17.2VulnerableOracle
cpe:2.3:a:oracle:instantis_enterprisetrack:17.3:*:*:*:*:*:*:*17.3VulnerableOracle
cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*not specified by NVDVulnerableNetApp
  • cpe:2.3:a:apache:http_server:2.4.49:*:*:*:*:*:*:* Versions 2.4.49 Vulnerable ·Apache
  • cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
  • cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* Versions 35 Vulnerable ·Fedoraproject
  • cpe:2.3:a:oracle:instantis_enterprisetrack:17.1:*:*:*:*:*:*:* Versions 17.1 Vulnerable ·Oracle
  • cpe:2.3:a:oracle:instantis_enterprisetrack:17.2:*:*:*:*:*:*:* Versions 17.2 Vulnerable ·Oracle
  • cpe:2.3:a:oracle:instantis_enterprisetrack:17.3:*:*:*:*:*:*:* Versions 17.3 Vulnerable ·Oracle
  • cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp

Remediation

No fixed version listed by the sources yet.

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Advisory ·

    Apache HTTP Server — 20211007 Apache HTTP Server Vulnerabilties: October 2021

    3 records Highest priority Priority CRITICAL 2 CRITICAL, 1 MEDIUM

    Other records, highest priority first

    • TI-2021-18535 Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)Priority CRITICAL 100
    • TI-2021-18264 null pointer dereference in h2 fuzzingPriority MEDIUM 54
    Show all 3 records → Advisory →
  • Advisory ·

    Apache HTTP Server — FEDORA-2021-2a10bc68a4

    2 records Highest priority Priority CRITICAL 2 CRITICAL

    Other records, highest priority first

    • TI-2021-18535 Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)Priority CRITICAL 100
    Show all 2 records → Advisory →
Show 1 more group
  • Advisory ·

    Apache HTTP Server — FEDORA-2021-aaf90ef84a

    2 records Highest priority Priority CRITICAL 2 CRITICAL

    Other records, highest priority first

    • TI-2021-18535 Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)Priority CRITICAL 100
    Show all 2 records → Advisory →

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Not affected: 7 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • Red Hat JBoss Core Services
  • Red Hat JBoss Enterprise Application Platform 6
  • Red Hat Software Collections

Timeline

  1. 2021-11-03 Added to CISA KEV
  2. 2026-10-02 Threatist record created from CVE-2021-41773
  3. 2026-10-03 Alias added: GHSA-29h7-gr57-5f8r

References

Exploit 6

Patch 4

Advisory 15

Other 4

  • TI-2021-18535 Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773) KEVCVSS 3.1CRITICAL 9.8
  • TI-2024-25716 Apache HTTP Server weakness in mod_rewrite when first segment of substitution matches filesystem path. KEVCVSS 3.1CRITICAL 9.1
  • TI-2021-17490 mod_proxy SSRF KEVCVSS 3.1CRITICAL 9.0
  • TI-2019-00184 Use after free in Apache HTTP Server KEVCVSS 3.1HIGH 7.8
  • TI-2009-03392 The TLS protocol, and the SSL protocol 3.0 and possibly earlier, as used in Microsoft… CVSS 3.1CRITICAL 9.8
  • TI-2023-10967 Apache HTTP Server: HTTP request splitting with mod_rewrite and mod_proxy CVSS 3.1CRITICAL 9.8
See all 349 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences