CVE-2026-25478VulnerabilityPublished 9 Feb 2026

CVE-2026-25478: litestar · Permissive Cross-domain Policy with Untrusted Domains

Affects litestarSource CVE Database V5

Not known to be exploited · CVSS 7.4 High : upgrade to 2.20.0 soon.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 3.1 base score

7.4High

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 38% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.20.0

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

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

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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Feb 2026
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 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 litestar to 2.20.0.

Affected software

Product	Affected	Fixed in
litestar-orglitestar	Affected <2.20.0	Fixed in 2.20.0

AI-suggested

1. Upgrade all litestar instances to version 2.20.0 or later, where the vulnerability is fixed by properly escaping regex metacharacters in allowed_origins_regex. 2. Audit current CORS configurations to identify any overly permissive or regex-based origin allowlists and replace them with explicit, validated origin lists where possible. 3. Implement runtime monitoring and logging of cross-origin requests to detect anomalous or unexpected origins attempting access. 4. Employ Web Application Firewalls (WAFs) with rules to block suspicious cross-origin requests that do not match expected patterns. 5. Educate developers and security teams about the risks of regex-based origin validation and encourage use of safer CORS libraries or configurations. 6. Conduct penetration testing focused on CORS policies to verify that no unauthorized origins can bypass restrictions. 7. For critical applications, consider additional layers of authentication or token validation on cross-origin requests to reduce risk of unauthorized data access.

Description

CVE-2026-25478 is a high-severity vulnerability in the litestar ASGI framework versions prior to 2.20.0. It arises from improper construction of the allowed_origins_regex used for CORS origin validation, where metacharacters in the allowlist are not escaped. This flaw allows malicious origins to bypass the intended restrictions, potentially enabling cross-domain attacks. Exploitation requires user interaction but no authentication, and it can lead to a breach of confidentiality by exposing sensitive data to untrusted domains. The vulnerability affects web applications using litestar for asynchronous server gateway interfaces, particularly those relying on CORS for security. Although no known exploits are currently in the wild, the vulnerability's nature and CVSS score of 7.4 indicate a significant risk. European organizations using litestar in web services should prioritize upgrading to version 2.

Impact

For European organizations, this vulnerability can lead to unauthorized data exposure through cross-origin requests, compromising confidentiality of sensitive information handled by web applications built on the litestar framework. Since litestar is an ASGI framework often used in Python-based asynchronous web services, organizations in sectors such as finance, healthcare, and government that rely on these technologies are at risk. The vulnerability allows attackers to craft malicious origins that bypass CORS restrictions, potentially enabling data theft or session hijacking if combined with other weaknesses. Although integrity and availability are not directly impacted, the breach of confidentiality can have severe regulatory and reputational consequences, especially under GDPR. The ease of exploitation (no privileges required and low complexity) increases the threat level. European companies with public-facing APIs or web applications using litestar should consider this vulnerability critical to address to prevent data leakage and maintain compliance with data protection laws.

CWE-942Permissive Cross-domain Security Policy with Untrusted Domains (opens in a new tab)
Variant weaknessOWASP Top 10 A02:2025: Security Misconfiguration (opens in a new tab)
The product uses a web-client protection mechanism such as a Content Security Policy (CSP) or cross-domain policy file, but the policy includes untrusted domains with which the web client is allowed to communicate.
Architecture and Design · Operation · Attack Surface Reduction
Define a restrictive Content Security Policy or cross-domain policy file.
Architecture and Design · Operation · Attack Surface Reduction
Avoid using wildcards in the CSP / cross-domain policy file. Any domain matching the wildcard expression will be implicitly trusted, and can perform two-way interaction with the target server.
Architecture and Design · Operation · Environment Hardening
For Flash, modify crossdomain.xml to use meta-policy options such as 'master-only' or 'none' to reduce the possibility of an attacker planting extraneous cross-domain policy files on a server.
OWASP ASVS 4.0.3
V8.3.8 (opens in a new tab)
V1.14.1 (opens in a new tab)
V13.4.2 (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 17 Feb 2026, 09:43 UTC

WeaknessesCWE-942

Technical details

References

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