VulnerabilityPublished 30 Mar 2023Updated 3 Nov 2025

CVE-2023-26116: angular · Regular Expression Denial of Service

Affects angularSource CVE Database V5

Public exploit available · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 1.6% chance of exploitation in 30 days – higher than 76% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Base metrics

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

Temporal metrics

Exploit Code Maturity: Proof-of-Concept

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: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within 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.
Exploit Code Maturity: Proof-of-Concept: Proof-of-concept exploit code is available, or an attack demonstration is not practical for most systems. The code or technique is not functional in all situations and may require substantial modification by a skilled attacker.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 30 Mar 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
CVSS exploit maturity: proof of concept public
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), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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

Affected software

Product	Affected	Fixed in
npmangular`pkg:npm/angular`Other threats	Affected =1.2.21	Fixed in–

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

AI-suggested

To mitigate CVE-2023-26116, European organizations should: 1) Upgrade Angular from version 1.2.21 to the latest supported version where the vulnerability is patched or no longer present. If upgrading is not immediately feasible, consider applying any available patches or backported fixes. 2) Implement strict input validation and size limits on data passed to angular.copy() or related functions to prevent large, malicious payloads from triggering the regex. 3) Employ Web Application Firewalls (WAFs) with rules designed to detect and block suspicious payloads that could exploit regex vulnerabilities. 4) Monitor application performance metrics and logs for unusual CPU spikes or slowdowns indicative of ReDoS attempts. 5) Conduct code reviews and security testing focusing on regular expression usage in legacy codebases. 6) Educate developers about the risks of inefficient regular expressions and encourage secure coding practices. 7) Isolate legacy applications behind network segmentation to reduce exposure. These steps collectively reduce the risk of exploitation and improve detection and response capabilities.

Description

Versions of the package angular from 1.2.21 are vulnerable to Regular Expression Denial of Service (ReDoS) via the angular.copy() utility function due to the usage of an insecure regular expression. Exploiting this vulnerability is possible by a large carefully-crafted input, which can result in catastrophic backtracking.

Impact

For European organizations, the primary impact of CVE-2023-26116 is the potential for denial of service attacks against web applications using Angular 1.2.21. This can lead to service unavailability, degraded user experience, and potential operational disruptions, especially for public-facing or critical internal applications. While the vulnerability does not compromise data confidentiality or integrity, the availability impact can affect business continuity and customer trust. Organizations in sectors relying on legacy web applications—such as government portals, financial services, and manufacturing—may face increased risk. Additionally, the exploitation could be used as part of a larger attack chain to distract or degrade defenses. The lack of required authentication and user interaction means attackers can exploit this remotely and at scale if the vulnerable application is exposed to the internet. The medium severity rating suggests moderate urgency but should not be ignored, particularly in environments where uptime is critical.

CWE-1333Inefficient Regular Expression Complexity (opens in a new tab)
Base weaknessLikelihood of exploit: High
The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
Architecture and Design
Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
System Configuration
Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.
Implementation
Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
Regular Expression Exponential Blowup (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Nov 2025, 20:20 UTC

WeaknessesCWE-1333

Technical details

References

Community reviews

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