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CVE-2023-27495

17
FAUCET Score

CVE-2023-27495 describes a bypass vulnerability in the @fastify/csrf-protection plugin, affecting Fastify servers using it in conjunction with @fastify/cookie. Attackers can fixate a _csrf cookie and forge valid CSRF tokens, circumventing protection, especially when the optional userInfo parameter is missing or predictable. This medium-severity vulnerability (CVSS 6.5) has a network attack vector, low attack complexity, and high impact on integrity, allowing unauthorized actions. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.1.0CPE matchmatch criteria
cpe:2.3:a:fastify:csrf-protection:*:*:*:*:*:node.js:*:*
>= 5.0.0, < 6.3.0CPE matchmatch criteria
cpe:2.3:a:fastify:csrf-protection:*:*:*:*:*:node.js:*:*

CVSS Data

CVSS version used by this source: 3.1

5.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
1.6
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.33%
Probability of exploitation in next 30 days
EPSS Percentile
25.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0033 is in the 26th percentile among its peer group of 26,236 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

github_advisorypatch availablevia nvd_reference
View patch
npmpatch availablevia ghsa
Product: @fastify/csrf-protectionFixed in: 4.1.0
npmpatch availablevia ghsa
Product: @fastify/csrf-protectionFixed in: 6.3.0

Vendor Advisories (2)

npmGHSA-qrgf-9gpc-vrxwmedium

Bypass of CSRF protection in the presence of predictable userInfo

Apr 20, 2023
redhatCVE-2023-27495Moderate

fastify-csrf: Bypass of CSRF protection in the presence of predictable userInfo

Apr 20, 2023

References

github.com / fastify/csrf-protection/commit/be3e5761f37aa05c7c1ac8ed44499c51ecec8058
Patch
github.com / fastify/csrf-protection/security/advisories/GHSA-qrgf-9gpc-vrxw
Vendor Advisory
cvedetails.com / cve/CVE-2021-29624
Third Party Advisory