VulnerabilityPublished 3 Jul 2023Updated 4 Nov 2025

CVE-2023-36053: django · ReDoS

Affects djangoSource CVE Database V5

Not known to be exploited · CVSS 7.5 High · fixed in 4.2.3 : patch django soon.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 2.9% chance of exploitation in 30 days – higher than 87% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.2.3, 4.1.10, 3.2.20

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

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

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: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 3 Jul 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 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

Upgrade django to 4.2.3, 4.1.10 or 3.2.20.

Affected software

Product	Affected	Fixed in
PyPIdjango`pkg:pypi/django`Other threats	Affected <3.2.20 <4.1.10 <4.2.3	Fixed in 3.2.20 4.1.10 4.2.3

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

AI-suggested

European organizations should immediately assess their Django deployments to identify affected versions. The primary mitigation is to upgrade Django to versions 3.2.20, 4.1.10, or 4.2.3 and later, where the vulnerability has been addressed. Until upgrades can be applied, organizations should implement input validation controls at the application or web server level to limit the number of domain labels processed by EmailValidator and URLValidator, effectively reducing the risk of triggering ReDoS conditions. Rate limiting and web application firewalls (WAFs) can help detect and block suspicious requests with abnormally long domain names or excessive subdomain counts. Monitoring application performance and logs for unusual spikes in CPU usage or request latency related to email or URL validation is recommended to detect potential exploitation attempts. Developers should review custom validation logic to avoid similar ReDoS patterns and consider alternative validation libraries that are resistant to such attacks. Finally, organizations should maintain an incident response plan to quickly address denial of service incidents and communicate transparently with stakeholders.

Description

In Django 3.2 before 3.2.20, 4 before 4.1.10, and 4.2 before 4.2.3, EmailValidator and URLValidator are subject to a potential ReDoS (regular expression denial of service) attack via a very large number of domain name labels of emails and URLs.

Impact

For European organizations, the primary impact of CVE-2023-36053 is on the availability of web applications built with affected Django versions. Exploitation can lead to denial of service conditions, causing downtime or degraded performance, which can disrupt business operations, customer access, and critical services. Organizations in sectors such as finance, healthcare, e-commerce, and government, which often rely on Django for web services, may face operational interruptions and reputational damage. Since the vulnerability can be exploited remotely without authentication, attackers can launch automated or targeted attacks at scale. The absence of confidentiality or integrity impact limits the risk of data breaches, but service unavailability can indirectly affect compliance with regulations like GDPR if it impairs user access or data processing. Additionally, organizations with high traffic volumes or public-facing APIs are at greater risk due to increased exposure. The potential for cascading effects exists if critical services become unavailable, impacting dependent systems or third-party integrations.

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 4 Nov 2025, 22:14 UTC

WeaknessesCWE-1333

Technical details

References

Community reviews

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