CVE-2026-73637: http server Use-After-Free — Fix

Description

Use after free 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 authentication state corruption via concurrent Digest authentication requests when AuthDigestNcCheck is enabled or AuthDigestNonceLifetime is set to 0. Users are recommended to upgrade to version 2.4.69, which fixes this issue.

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CVSS v3.1 Score

7.3

HIGH

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

EPSS — Exploit Prediction

0.0048

Probability of exploitation

0.40%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-416 Use After Free

Affected Products

Vendor	Product	Versions
apache	http_server	2.4.0 — 2.4.69

References

Advisories & Patches

https://httpd.apache.org/security/vulnerabilities_24.html

Other References

http://www.openwall.com/lists/oss-security/2026/10/01/28

Frequently Asked Questions

What is CVE-2026-73637? +

Use after free 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 authentication state corruption via concurrent Digest authentication requests when AuthDigestNcCheck is enabled or AuthDigestNonceLifetime is set to 0. Users are recommended to upgrade to version 2.4.69, which fixes this issue. It has a CVSS v3.1 base score of 7.3 (HIGH).

How severe is CVE-2026-73637? +

CVE-2026-73637 has a CVSS v3.1 score of 7.3 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0048, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-73637? +

CVE-2026-73637 affects products from apache, specifically: http_server. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-73637? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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