CVE-2023-26118VulnerabilityPublished 30 Mar 2023Updated 3 Nov 2025

CVE-2023-26118: angular · Regular Expression Denial of Service (ReDoS)

Affects angularSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 06:26 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: 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 2026-10-26.

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 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 =1.4.9	Fixed in–

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

AI-suggested

1. Upgrade Angular from version 1.4.9 to the latest stable release where this vulnerability is fixed, as relying on outdated frameworks increases security risks. 2. If upgrading is not immediately feasible, implement server-side input validation to reject overly long or suspicious URL inputs before they reach the vulnerable regex processing. 3. Apply rate limiting and request throttling on endpoints accepting URL inputs to reduce the impact of potential ReDoS attacks. 4. Use Web Application Firewalls (WAFs) configured to detect and block anomalous input patterns that could trigger catastrophic backtracking. 5. Monitor application performance metrics and logs for signs of unusual CPU spikes or slowdowns indicative of ReDoS exploitation attempts. 6. Educate development teams about the risks of insecure regular expressions and encourage secure coding practices, including the use of safe regex patterns and input sanitization. 7. Conduct security testing, including fuzzing and regex performance testing, on input validation components to identify and remediate similar vulnerabilities proactively. 8. Maintain an inventory of legacy software components and prioritize their upgrade or replacement to reduce attack surface.

Description

Versions of the package angular from 1.4.9 are vulnerable to Regular Expression Denial of Service (ReDoS) via the <input type="url"> element due to the usage of an insecure regular expression in the input[url] functionality. 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-2023-26118 is on the availability of web applications that use Angular 1.4.9 and accept URL inputs via the vulnerable <input type="url"> element. An attacker can remotely trigger high CPU usage on client or server-side components processing the input, causing application slowdowns or crashes. This can disrupt business operations, degrade user experience, and potentially lead to service outages. Since the vulnerability does not affect confidentiality or integrity, data breaches or unauthorized data modifications are not a concern here. However, denial of service attacks can be leveraged as part of larger attack campaigns or to distract from other malicious activities. European organizations with legacy web applications, especially in sectors like government, finance, and critical infrastructure, may face operational risks if they have not updated Angular or implemented compensating controls. The medium severity score suggests moderate risk, but the ease of exploitation and lack of authentication requirements increase the threat landscape. Additionally, public-facing applications are more exposed, increasing the likelihood of exploitation attempts. The absence of known exploits in the wild reduces immediate risk but does not eliminate the need for mitigation.

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

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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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