CVE-2024-38475

Apache HTTP Server: Improper Escaping of Output

As of , CVE-2024-38475 in Apache HTTP Server is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch this week.

Exploited
Yes: CISA listed it on 1 May 2025
US federal deadline
22 May 202521 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
Not known to CISA
EPSS score
0.99Higher than 99% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
Public exploit
None foundNeither Metasploit nor Exploit-DB lists one.
Fix
Vendor advice: httpd.apache.orgLinks below, from CISA's entry.

What CISA says to do

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

CISA's required action

  • httpd.apache.orgThis vulnerability affects a common open-source component, third-party library, or a protocol used by different products. Please check…

What the flaw is

Apache HTTP Server contains an improper escaping of output vulnerability in mod_rewrite that allows an attacker to map URLs to filesystem locations that are permitted to be served by the server but are not intentionally/directly reachable by any URL, resulting in code execution or source code disclosure.

CISA's description

Improper escaping of output in mod_rewrite in Apache HTTP Server 2.4.59 and earlier allows an attacker to map URLs to filesystem locations that are permitted to be served by the server but are not intentionally/directly reachable by any URL, resulting in code execution or source code disclosure. Substitutions in server context that use a backreferences or variables as the first segment of the substitution are affected. Some unsafe RewiteRules will be broken by this change and the rewrite flag "UnsafePrefixStat" can be used to opt back in once ensuring the substitution is appropriately constrained.

The CVE record's description, from apache

CVE published
1 July 2024
Assigned by
apache
CVSS
9.1 Critical (CVSS 3.1, from CISA-ADP)
CWE-116
Improper Encoding or Escaping of Output
CISA SSVC, exploitation
active
CISA SSVC, automatable
yes
CISA SSVC, technical impact
total

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.

HTTP Server: other exploited entries

VulnerabilityProductOur groupListedDeadlineEPSS
CVE-2021-41773Path TraversalApache HTTP ServerPatch this weekRansomware use; Metasploit module; EPSS 0.99; verified Exploit-DB entry0.99
CVE-2021-42013Path TraversalApache HTTP ServerPatch this weekRansomware use; Metasploit module; EPSS 0.99; verified Exploit-DB entry0.99
CVE-2019-0211Privilege EscalationApache HTTP ServerPatch this weekEPSS 0.650.65

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