VulnerabilityPublished 5 Dec 2025

CVE-2025-66200: Apache HTTP Server · mod_userdir+suexec bypass via AllowOverride FileInfo

Affects Apache HTTP ServerSource CVE Database V5

Not known to be exploited · CVSS 5.4 Medium · fixed in 2.4.66 : update Apache HTTP Server when convenient.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

5.4Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.6% chance of exploitation in 30 days – higher than 50% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.4.66

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 5 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Apacheapache/httpd`pkg:rpm/apache/httpd`Other threats	Affected =2.4.7	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade Apache HTTP Server to version 2.4.66 or later immediately to apply the official patch addressing this vulnerability.
Review and restrict the use of AllowOverride directives, particularly limiting or disabling FileInfo overrides in .htaccess files unless absolutely necessary.
Audit all .htaccess files for the use of the RequestHeader directive and remove or restrict permissions for untrusted users to modify these files.
Harden suexec configurations by ensuring that only trusted users can deploy CGI scripts and that suexec wrappers are properly configured to enforce user boundaries.
Implement strict access controls on web server directories to prevent unauthorized modifications to .htaccess files.
Monitor web server logs for unusual CGI script executions or unexpected user IDs running scripts, which may indicate exploitation attempts.
Employ web application firewalls (WAFs) to detect and block suspicious HTTP header manipulations related to RequestHeader usage.
Conduct regular security assessments and penetration testing focusing on web server configurations and privilege boundaries to detect similar misconfigurations.

Description

mod_userdir+suexec bypass via AllowOverride FileInfo vulnerability in Apache HTTP Server. Users with access to use the RequestHeader directive in htaccess can cause some CGI scripts to run under an unexpected userid. This issue affects Apache HTTP Server: from 2.4.7 through 2.4.65. Users are recommended to upgrade to version 2.4.66, which fixes the issue.

Impact

For European organizations, this vulnerability poses a risk primarily to web servers running affected Apache HTTP Server versions with suexec enabled and AllowOverride set to FileInfo, permitting RequestHeader usage in .htaccess files. Exploitation could allow attackers with limited privileges to execute CGI scripts under unauthorized user IDs, potentially leading to privilege escalation or unauthorized actions on the server. This can compromise the integrity of hosted applications and may disrupt availability if malicious scripts are executed. While confidentiality is not directly impacted, the ability to run scripts under different user contexts can facilitate further attacks or lateral movement within the network. Organizations relying on Apache for hosting critical web services, especially those using shared hosting environments or multi-user setups, are at higher risk. The vulnerability could also affect compliance with European data protection regulations if exploited to alter or disrupt services. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially given the widespread use of Apache HTTP Server across Europe.

CWE-288Authentication Bypass Using an Alternate Path or Channel (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product requires authentication, but the product has an alternate path or channel that does not require authentication.
Architecture and Design
Funnel all access through a single choke point to simplify how users can access a resource. For every access, perform a check to determine if the user has permissions to access the resource.
OWASP Cheat Sheets
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V1.2.3 (opens in a new tab)
V1.2.2 (opens in a new tab)
V1.2.4 (opens in a new tab)
Attack patterns
Directory Indexing (opens in a new tab)
Exploitation of Thunderbolt Protection Flaws (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 12 Dec 2025, 11:55 UTC

WeaknessesCWE-288

Technical details

References

Community reviews

Related threats