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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V15 - Secure Coding and Architecture Concurrency control, locking
MITRE ATT&CK

1 technique across 1 tactic: Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 7.5 (HIGH). Attack characteristics: network attack vector, high complexity, low privileges required, no user interaction not required.

Exploit ScenarioDerived

This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the high-severity affected system.

This Week Schedule remediation this week. Why: HIGH severity + EPSS > 10%.
Patch available 17.7% exploitation probability (EPSS)

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AnalysisAI

In Apache HTTP Server 2.4 release 2.4.38 and prior, a race condition in mod_auth_digest when running in a threaded server could allow a user with valid credentials to authenticate using another. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-362. In Apache HTTP Server 2.4 release 2.4.38 and prior, a race condition in mod_auth_digest when running in a threaded server could allow a user with valid credentials to authenticate using another username, bypassing configured access control restrictions. Affected products include: Apache Http Server, Debian Debian Linux, Fedoraproject Fedora, Canonical Ubuntu Linux, Redhat Enterprise Linux.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.5 HIGH
AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

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

DescriptionNVD

In Apache HTTP Server 2.4 release 2.4.38 and prior, a race condition in mod_auth_digest when running in a threaded server could allow a user with valid credentials to authenticate using another username, bypassing configured access control restrictions.

Threat Intelligence Overview

EPSS Score
17.7%
Top 3% exploitable
Data Quality
2 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 17.7%
Patch available Yes
Active threat No
Deciding rule
HIGH severity + EPSS > 10%
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

56
Low Medium High Critical
KEV: 0
EPSS: +18
CVSS: +38
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Race conditions occur when multiple concurrent requests exploit the brief time gap between checking a condition and acting upon it (TOCTOU - Time of Check, Time of Use).

Affected Products (CPE)NVD

cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:28:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:29:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:esm:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:-:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_desktop:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_server:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_workstation:7.0:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.0:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:42.3:*:*:*:*:*:*:*
cpe:2.3:a:netapp:oncommand_unified_manager:-:*:*:*:*:7-mode:*:*
cpe:2.3:o:netapp:clustered_data_ontap:-:*:*:*:*:*:*:*
cpe:2.3:a:oracle:enterprise_manager_ops_center:12.3.3:*:*:*:*:*:*:*
+ 4 more
CVE-2021-40438 CRITICAL POC
9.0 Sep 16

A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user.4.4

CVE-2023-44487 HIGH POC
7.5 Oct 10

Denial of service against HTTP/2 server implementations allows remote unauthenticated attackers to exhaust server resour

CVE-2017-9798 HIGH POC
7.5 Sep 18

Apache httpd allows remote attackers to read secret data from process memory if the Limit directive can be set in a user

CVE-2013-2566 MEDIUM POC
5.9 Mar 15

The RC4 algorithm, as used in the TLS protocol and SSL protocol, has many single-byte biases, which makes it easier for

CVE-2014-0226 MEDIUM POC
6.8 Jul 20

Race condition in the mod_status module in the Apache HTTP Server before 2.4.10 allows remote attackers to cause a denia

CVE-2016-8740 HIGH POC
7.5 Dec 05

The mod_http2 module in the Apache HTTP Server 2.4.17 through 2.4.23, when the Protocols configuration includes h2 or h2

CVE-2026-21962 CRITICAL POC
10.0 Jan 20

Oracle HTTP Server and WebLogic Server Proxy Plug-in have a CVSS 10.0 access control vulnerability allowing unauthentica

CVE-2020-1967 HIGH POC
7.5 Apr 21

Server or client applications that call the SSL_check_chain() function during or after a TLS 1.3 handshake may crash due

CVE-2013-5704 MEDIUM POC
5.0 Apr 15

The mod_headers module in the Apache HTTP Server 2.2.22 allows remote attackers to bypass "RequestHeader unset" directiv

CVE-2013-2249 HIGH POC
7.5 Jul 23

mod_session_dbd.c in the mod_session_dbd module in the Apache HTTP Server before 2.4.5 proceeds with save operations for

CVE-2016-5387 HIGH
8.1 Jul 19

The Apache HTTP Server through 2.4.23 follows RFC 3875 section 4.1.18 and therefore does not protect applications from t

CVE-2017-7668 HIGH
7.5 Jun 20

The HTTP strict parsing changes added in Apache httpd 2.2.32 and 2.4.24 introduced a bug in token list parsing, which al

References

Advisories & patches
PATCH https://www.oracle.com/technetwork/security-advisory/cpujul2019-5072835.html ADVISORY https://httpd.apache.org/security/vulnerabilities_24.html REF http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00051.html REF http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00061.html REF http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00084.html REF http://www.openwall.com/lists/oss-security/2019/04/02/5 REF http://www.securityfocus.com/bid/107668 REF https://access.redhat.com/errata/RHSA-2019:2343 REF https://access.redhat.com/errata/RHSA-2019:3436 REF https://access.redhat.com/errata/RHSA-2019:3932 REF https://access.redhat.com/errata/RHSA-2019:3933 REF https://access.redhat.com/errata/RHSA-2019:3935 REF https://access.redhat.com/errata/RHSA-2019:4126 REF https://bugzilla.redhat.com/show_bug.cgi?id=1695020 REF https://lists.apache.org/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba%40%3Ccvs.httpd.apache.org%3E REF https://lists.apache.org/thread.html/84a3714f0878781f6ed84473d1a503d2cc382277e100450209231830%40%3Ccvs.httpd.apache.org%3E REF https://lists.apache.org/thread.html/e0b8f6e858b1c8ec2ce8e291a2c543d438915037c7af661ab6d33808%40%3Cdev.httpd.apache.org%3E REF https://lists.apache.org/thread.html/r03ee478b3dda3e381fd6189366fa7af97c980d2f602846eef935277d%40%3Ccvs.httpd.apache.org%3E REF https://lists.apache.org/thread.html/r06f0d87ebb6d59ed8379633f36f72f5b1f79cadfda72ede0830b42cf%40%3Ccvs.httpd.apache.org%3E REF https://lists.apache.org/thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E REF https://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E REF https://lists.apache.org/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E REF https://lists.apache.org/thread.html/rd18c3c43602e66f9cdcf09f1de233804975b9572b0456cc582390b6f%40%3Ccvs.httpd.apache.org%3E REF https://lists.apache.org/thread.html/rd2fb621142e7fa187cfe12d7137bf66e7234abcbbcd800074c84a538%40%3Ccvs.httpd.apache.org%3E REF https://lists.apache.org/thread.html/re3d27b6250aa8548b8845d314bb8a350b3df326cacbbfdfe4d455234%40%3Ccvs.httpd.apache.org%3E REF https://lists.apache.org/thread.html/re473305a65b4db888e3556e4dae10c2a04ee89dcff2e26ecdbd860a9%40%3Ccvs.httpd.apache.org%3E REF https://lists.apache.org/thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.apache.org%3E REF https://lists.debian.org/debian-lts-announce/2019/04/msg00008.html REF https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ALIR5S3O7NRHEGFMIDMUSYQIZOE4TJJN/ REF https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EZRMTEIGZKYFNGIDOTXN3GNEJTLVCYU7/ REF https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WETXNQWNQLWHV6XNW6YTO5UGDTIWAQGT/ REF https://seclists.org/bugtraq/2019/Apr/5 REF https://security.netapp.com/advisory/ntap-20190423-0001/ REF https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03950en_us REF https://usn.ubuntu.com/3937-1/ REF https://usn.ubuntu.com/3937-2/ REF https://www.debian.org/security/2019/dsa-4422 REF https://www.oracle.com/security-alerts/cpuapr2020.html REF https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html

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