CVE-2026-25480VulnerabilityPublished 9 Feb 2026

CVE-2026-25480: litestar · Improper Handling of Unicode Encoding

Affects litestarSource CVE Database V5

Not known to be exploited · CVSS 6.5 Medium : upgrade to 2.20.0 when convenient.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 3.1 base score

6.5Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 40% 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:N/S:U/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
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: 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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on 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

The primary and most effective mitigation is to upgrade all litestar deployments to version 2.20.0 or later, where the cache key collision issue is resolved. Organizations should audit their use of the FileStore cache backend and assess whether any cached responses could have been affected. For environments where immediate upgrade is not feasible, consider disabling the FileStore response cache backend or replacing it with alternative caching mechanisms that properly handle Unicode normalization and key separation. Implement monitoring to detect unusual cache behavior or unexpected content served from cache. Additionally, review application-level input validation and normalization of URL paths to reduce the risk of crafted inputs triggering cache collisions. Security teams should also ensure that web application firewalls (WAFs) and intrusion detection systems are tuned to detect anomalous requests that might exploit this vulnerability. Finally, maintain an inventory of affected systems and ensure timely patch management processes are in place to prevent exploitation.

Description

CVE-2026-25480 is a medium severity vulnerability in the litestar ASGI framework versions prior to 2.20.0. It arises from improper handling of Unicode normalization in the FileStore cache backend, which maps cache keys to filenames using Unicode NFKD normalization and ord() substitution without separators. This flawed approach can cause cache key collisions when an unauthenticated remote attacker crafts specific URL paths, leading to cache poisoning or response mixups where one URL serves cached responses intended for another. The vulnerability does not require authentication or user interaction and impacts confidentiality and integrity by exposing or mixing cached data. It is fixed in litestar version 2.20.0. European organizations using vulnerable litestar versions as part of their web infrastructure may face risks of data leakage or incorrect content delivery.

Impact

For European organizations using litestar versions prior to 2.20.0, particularly those employing the FileStore cache backend for response caching, this vulnerability poses a risk of cache poisoning. This can lead to unauthorized disclosure of cached content, potentially exposing sensitive information across different users or requests. Additionally, integrity of served content can be compromised, resulting in users receiving incorrect or maliciously altered responses. While availability is not directly impacted, the trustworthiness and confidentiality of web applications relying on litestar caching are at risk. Organizations in sectors handling sensitive data—such as finance, healthcare, and government—may face regulatory and reputational consequences if such data leakage occurs. The vulnerability's ease of exploitation without authentication increases risk, especially for public-facing web services. However, the absence of known exploits in the wild suggests limited active exploitation currently, but proactive mitigation is critical to prevent future attacks.

CWE-176Improper Handling of Unicode Encoding (opens in a new tab)
Variant weakness
The product does not properly handle when an input contains Unicode encoding.
Architecture and Design · Input Validation
Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
OWASP Cheat Sheets
Unvalidated Redirects and Forwards (opens in a new tab)
XML Security (opens in a new tab)
XML External Entity Prevention (opens in a new tab)
File Upload (opens in a new tab)
Input Validation (opens in a new tab)
OWASP ASVS 4.0.3
V5.3.2 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
Using Unicode Encoding to Bypass Validation Logic (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 17 Feb 2026, 09:44 UTC

WeaknessesCWE-176

Technical details

References

Community reviews

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