Litestar has a CORS origin allowlist bypass due to unescaped regex metacharacters in allowed origins

published 2026-02-09 8 mo ago modified 2026-07-13 3 mo ago also EUVD-2026-6496 , GHSA-2p2x-hpg8-cqp2 , PYSEC-2026-2195

cvss: 7.4; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits: 0; none known

Litestar is an Asynchronous Server Gateway Interface (ASGI) framework. Prior to 2.20.0, CORSConfig.allowed_origins_regex is constructed using a regex built from configured allowlist values and used with fullmatch() for validation. Because metacharacters are not escaped, a malicious origin can match unexpectedly. The check relies on allowed_origins_regex.fullmatch(origin). This vulnerability is fixed in 2.20.0.

Patch / fix

fixed in 2 links 2

pypi litestar 2.20.0
litestar litestar 2.20.0

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 8 mo ago (2026-02-10)

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/litestar-org/litestar/security/advisories/GHSA-2p2x-hpg8-cqp2 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.4	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N
GitHub	3.1	7.4	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N
NVD	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
OSV	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Affected packages

ecosystem	package	affected	fixed in
pypi	litestar	>=2.19.0, <2.20.0 <2.20.0	2.20.0

Affected products

litestar-org litestar

Classification

Weakness

CWE-942 Permissive Cross-domain Security Policy with Untrusted Domains

References

github.com /litestar-org/litestar/commit/eb87703b309efcc0d1b087dcb12784e76b003d5a
web, patch
github.com /litestar-org/litestar/security/advisories/GHSA-2p2x-hpg8-cqp2
web, exploit, vendor-advisory, evidence
docs.litestar.dev /2/release-notes/changelog.html#2.20.0
web, release-notes, advisory
github.com /litestar-org/litestar/releases/tag/v2.20.0
web, release-notes, advisory
nvd.nist.gov /vuln/detail/CVE-2026-25478
advisory
github.com /litestar-org/litestar
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary