Security Resilience

CVE-2023-23621

Discourse ≤ 3.0.1

Published
28 January 2023
Modified
21 November 2024
Patch / advisory
View advisory
CVSS Score v3.1 8.6
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS Score 0.0087 58th percentile
Risk Priority 63 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-23621 is a high-severity Inefficient Regular Expression Complexity (CWE-1333) vulnerability in Discourse Discourse. Its CVSS base score is 8.6 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique OS Credential Dumping (T1003); ranked in the top 42% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability Data

Discourse is an open-source discussion platform. Prior to version 3.0.1 on the `stable` branch and version 3.1.0.beta2 on the `beta` and `tests-passed` branches, a malicious user can cause a regular expression denial of service using a carefully crafted user agent.…

more

This issue is patched in version 3.0.1 on the `stable` branch and version 3.1.0.beta2 on the `beta` and `tests-passed` branches. There are no known workarounds.

CWE(s)
CWE-1333

Related Threats

MITRE ATT&CK Enterprise Techniques

T1003 OS Credential Dumping Credential Access
Adversaries may attempt to dump credentials to obtain account login and credential material, normally in the form of a hash or a clear text password.
attack.mitre.org →
T1003.003 NTDS Credential Access
Adversaries may attempt to access or create a copy of the Active Directory domain database in order to steal credential information, as well as obtain other information about domain members such as devices, users, and access rights.
attack.mitre.org →
T1003.006 DCSync Credential Access
Adversaries may attempt to access credentials and other sensitive information by abusing a Windows Domain Controller's application programming interface (API)(Citation: Microsoft DRSR Dec 2017) (Citation: Microsoft GetNCCChanges) (Citati…
attack.mitre.org →
T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
T1008 Fallback Channels Command And Control
Adversaries may use fallback or alternate communication channels if the primary channel is compromised or inaccessible in order to maintain reliable command and control and to avoid data transfer thresholds.
attack.mitre.org →
T1012 Query Registry Discovery
Adversaries may interact with the Windows Registry to gather information about the system, configuration, and installed software.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-25167Same product: Discourse Discourse
CVE-2023-45806Same product: Discourse Discourse
CVE-2023-22740Same product: Discourse Discourse
CVE-2023-40588Same product: Discourse Discourse
CVE-2023-41043Same product: Discourse Discourse
CVE-2025-68659Same product: Discourse Discourse
CVE-2024-21655Same product: Discourse Discourse
CVE-2023-28107Same product: Discourse Discourse
CVE-2023-46130Same product: Discourse Discourse
CVE-2023-47120Same product: Discourse Discourse

Affected Assets

discourse
discourse
1.1.0, 1.2.0, 1.3.0, 1.4.0, 1.5.0 · ≤ 3.0.1

Mitigating Controls

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

ID.RA-01 partial match
blocks

Vulnerability identification processes can discover ReDoS issues in existing code but do not stop their introduction.

PR.PS-06 partial match
blocks

Secure SDLC practices directly prevent inefficient regex via reviews, static analysis, and safe libraries.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.8.10 Information deletion partial match
removes

References