CVE-2026-73637VulnerabilityPublished 1 Oct 2026Updated 9 Nov 2026

Apache2: Use after free

Affects apache2Source GCVE Database

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Authoritative record:CVE-2026-73637· High 7.3

Not known to be exploited · CVSS 7.3 High · fixed in 2.4.7-1ubuntu4.22+esm17 : patch apache2 soon.

Data as of 10 Nov 2026, 06:24 UTC

CVSS 3.1 base score

7.3High

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

Patch: Available – fixed in 2.4.7-1ubuntu4.22+esm17, 2.4.18-2ubuntu3.17+esm22, 2.4.29-1ubuntu4.27+esm13 +4

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
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: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to 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 1 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 9 Nov 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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

Upgrade to a fixed release listed under Affected software.

Patches and advisories

ubuntu.com/security/notices/USN-8931-1 (opens in a new tab)

Affected software

Product	Affected	Fixed in
Ubuntu 26.10apache2`pkg:deb/ubuntu/apache2?arch=source&distro=stonking`Other threats	Affected =2.4.66-2ubuntu2 =2.4.68-1ubuntu4 =2.4.68-1ubuntu6.1	Fixed in–
Ubuntu 26.04 LTSapache2`pkg:deb/ubuntu/apache2?arch=source&distro=resolute`Other threats	Affected <2.4.66-2ubuntu2.6	Fixed in 2.4.66-2ubuntu2.6
Ubuntu 24.04 LTSapache2`pkg:deb/ubuntu/apache2?arch=source&distro=noble`Other threats	Affected <2.4.58-1ubuntu8.17	Fixed in 2.4.58-1ubuntu8.17
Ubuntu 22.04 LTSapache2`pkg:deb/ubuntu/apache2?arch=source&distro=jammy`Other threats	Affected <2.4.52-1ubuntu4.25	Fixed in 2.4.52-1ubuntu4.25
Ubuntu Pro 20.04 LTSapache2`pkg:deb/ubuntu/apache2?arch=source&distro=esm-infra/focal`Other threats	Affected <2.4.41-4ubuntu3.23+esm9	Fixed in 2.4.41-4ubuntu3.23+esm9
Ubuntu Pro 18.04 LTSapache2`pkg:deb/ubuntu/apache2?arch=source&distro=esm-infra/bionic`Other threats	Affected <2.4.29-1ubuntu4.27+esm13	Fixed in 2.4.29-1ubuntu4.27+esm13

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

AI-suggested

Users should upgrade Apache HTTP Server to version 2.4.69 or later. Ubuntu users should apply the security updates provided in the Ubuntu Security Notice USN-8931-1, which includes fixed package versions for multiple Ubuntu LTS releases. Standard system updates will apply the necessary fixes. No additional mitigation is required beyond applying these official patches.

Description

A use-after-free vulnerability exists in the mod_auth_digest module of Apache HTTP Server versions prior to 2.4.69. This flaw allows an unauthenticated remote attacker to cause authentication state corruption by sending concurrent Digest authentication requests when specific configuration options (AuthDigestNcCheck enabled or AuthDigestNonceLifetime set to 0) are used. The issue is fixed in Apache HTTP Server version 2.4.69 and later.

Impact

An unauthenticated remote attacker can exploit this vulnerability to corrupt the authentication state in Apache HTTP Server, potentially leading to denial of service or other impacts on confidentiality and integrity of authentication. The flaw affects all platforms running vulnerable versions of Apache HTTP Server with the mod_auth_digest module configured with AuthDigestNcCheck enabled or AuthDigestNonceLifetime set to 0.

References

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