CVE-2026-93546
Description
A flaw was found in httpd. An integer overflow in the mod_dav_fs module occurs when processing Web Distributed Authoring and Versioning (WebDAV) PROPPATCH requests that declare an excessive number of XML namespaces. An authenticated remote attacker with write access can exploit this flaw to crash server worker processes, causing a Denial of Service (DoS), and persistently corrupt the directory's property database.
Mitigation
If WebDAV capabilities are not required, disable the `mod_dav_fs` module:
1. Comment out the `dav_fs_module` directive in `/etc/httpd/conf.modules.d/00-dav.conf`:
#LoadModule dav_fs_module modules/mod_dav_fs.so
Alternatively, if WebDAV is required but property modifications can be restricted, block the `PROPPATCH` method in the affected `<Directory>` or `<Location>` configuration block:
apache
<Location "/webdav">
<Limit PROPPATCH>
Require all denied
</Limit>
</Location>
2. Apply the configuration changes:
systemctl reload httpd
Caveats:
Disabling `mod_dav_fs` disables file-backed WebDAV shares across the server. Blocking `PROPPATCH` prevents clients from manipulating WebDAV dead properties.
Warning: Reloading or restarting the `httpd` service will temporarily impact active client connections.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.4 | N/A | 8.8 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | Low | N/A | High |
| Availability Impact | Low | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (Memory); DoS: Instability
This weakness can generally lead to undefined behavior and therefore crashes. When the calculated result is used for resource allocation, this weakness can cause too many (or too few) resources to be allocated, possibly enabling crashes if the product requests more resources than can be provided.
Integrity
Technical Impact: Modify Memory
If the value in question is important to data (as opposed to flow), simple data corruption has occurred. Also, if the overflow/wraparound results in other conditions such as buffer overflows, further memory corruption may occur.
Confidentiality,Availability,Access Control
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism
This weakness can sometimes trigger buffer overflows, which can be used to execute arbitrary code. This is usually outside the scope of the product's implicit security policy.
Availability,Other
Technical Impact: Alter Execution Logic; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU)
If the overflow/wraparound occurs in a loop index variable, this could cause the loop to terminate at the wrong time - too early, too late, or not at all (i.e., infinite loops). With too many iterations, some loops could consume too many resources such as memory, file handles, etc., possibly leading to a crash or other DoS.
Access Control
Technical Impact: Bypass Protection Mechanism
If integer values are used in security-critical decisions, such as calculating quotas or allocation limits, integer overflows can be used to cause an incorrect security decision.
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