high CVSS 7.5

CVE-2026-48005·Apache vulnerability

Missing authentication checks in mod_auth_digest in Apache Software Foundation Apache HTTP Server before 2.4.69 on all platforms allows an unauthenticated remote client to cause a denial of service (forced re-authentication) via forged Authorization headers when Digest authentication is enabled with AuthDigestNcCheck . Users are recommended to upgrade to version 2.4.69, which fixes this issue.

Severity
high
Software
Apache
Fixed in
2.4.69
Published
2026-10-01

Affected versions

From: 2.4.0

Until: 2.4.69

Fixed in: 2.4.69

How to fix this CVE

Upgrade Apache HTTP Server to version 2.4.69 or later to patch the authentication bypass vulnerability in mod_auth_digest. This update eliminates the weakness that allows attackers to forge digest authentication headers and trigger service disruption. If you are currently running versions 2.4.0 through 2.4.68 with Digest authentication enabled, immediate patching is recommended to restore proper authentication validation.

sudo dnf update httpd httpd-tools

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST|GET /.*HTTP.*Authorization:.*Digest.*nc=([0-9a-fA-F]+).*qop=auth|Multiple 401 responses to same endpoint from same source IP within 60 seconds|Authorization header with mismatched nonce value in repeated requests

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Implement a WAF rule to rate-limit or block requests from single IPs sending multiple Authorization headers with varying digest values within a short timeframe. Alternatively, block requests with malformed or duplicate Digest authentication parameters.

How to check if you are affected

  1. Check Apache version: apache2ctl -v or httpd -v — confirm installed version is 2.4.68 or earlier
  2. Verify Digest authentication is enabled: grep -i 'AuthDigestNcCheck' /etc/apache2/mods-enabled/*.conf or /etc/httpd/conf.d/*.conf
  3. Search access and error logs for repeated 401 responses from single IP: grep '401' /var/log/apache2/access.log | cut -d' ' -f1 | sort | uniq -c | sort -rn
  4. Confirm patch applied: apache2ctl -v or httpd -v should show 2.4.69 or later after upgrade completion

FAQ

What is CVE-2026-48005?

CVE-2026-48005 is an authentication bypass vulnerability in Apache mod_auth_digest that allows unauthenticated remote attackers to craft forged Authorization headers and force legitimate users to re-authenticate, causing a denial of service when AuthDigestNcCheck is enabled.

Is CVE-2026-48005 being actively exploited?

No, CVE-2026-48005 is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploit code is currently available. However, the vulnerability is straightforward to exploit and should still be patched promptly.

What versions of Apache are affected by CVE-2026-48005?

Apache HTTP Server versions 2.4.0 through 2.4.68 are vulnerable. Version 2.4.69 and later contain the fix.

How do I check if my server is vulnerable to CVE-2026-48005?

Run 'httpd -v' or 'apache2ctl -v' and verify the version number. If it shows 2.4.68 or earlier and Digest authentication is enabled (check 'grep AuthDigest /etc/httpd/conf.d/*.conf'), your server is vulnerable.

Does Defensia detect CVE-2026-48005?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Apache is installed on a monitored server, CVE-2026-48005 will appear in your dashboard with remediation steps.

Related Apache CVEs

CVE-2021-41773CVSS 10A 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.
CVE-2021-42013CVSS 10It was found that the fix for CVE-2021-41773 in Apache HTTP Server 2.4.50 was insufficient. 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 only affects Apache 2.4.49 and Apache 2.4.50 and not earlier versions.
CVE-2024-38474CVSS 9.8Substitution encoding issue in mod_rewrite in Apache HTTP Server 2.4.59 and earlier allows attacker to execute scripts in directories permitted by the configuration but not directly reachable by any URL or source disclosure of scripts meant to only to be executed as CGI. Users are recommended to upgrade to version 2.4.60, which fixes this issue. Some RewriteRules that capture and substitute unsafely will now fail unless rewrite flag "UnsafeAllow3F" is specified.
CVE-2024-38476CVSS 9.8Vulnerability in core of Apache HTTP Server 2.4.59 and earlier are vulnerably to information disclosure, SSRF or local script execution via backend applications whose response headers are malicious or exploitable. Users are recommended to upgrade to version 2.4.60, which fixes this issue.
CVE-2026-28780CVSS 9.8Heap-based Buffer Overflow vulnerability in mod_proxy_ajp of Apache HTTP Server. If mod_proxy_ajp connects to a malicious AJP server this AJP server can send a malicious AJP message back to mod_proxy_ajp and cause it to write 4 attacker controlled bytes after the end of a heap based buffer. This issue affects Apache HTTP Server: through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

References

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