CVE-2026-25479Public exploitNetwork attack vector

Host allowlist bypass via unescaped regex metacharacters

Published Feb 9, 2026 · Updated Feb 9, 2026

Host allowlist bypass in Litestar before 2.20.0 allows remote attackers to submit unintended hostnames via crafted Host headers. AllowedHostsMiddleware joins configured hostnames into a regular expression without escaping metacharacters, so a dot can match any character. The flaw is reachable only when an application enables AllowedHosts, and downstream impact depends on how it trusts validated hostnames.

CVSS severity6.5
Medium
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Host allowlist bypass in Litestar before 2.20.0 allows remote attackers to submit unintended hostnames via crafted Host headers. AllowedHostsMiddleware joins configured hostnames into a regular expression without escaping metacharacters, so a dot can match any character. The flaw is reachable only when an application enables AllowedHosts, and downstream impact depends on how it trusts validated hostnames.

The record

CVE
CVE-2026-25479
Published
Feb 9, 2026
Updated
Feb 9, 2026
Vendor
Litestar
Product
Litestar
Classifications
CWE-185, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.20.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Litestar · Litestarversion=< 2.20.0

Published CVSS scores

6.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-185Incorrect Regular Expression
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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