GHSA-hv23-4qp7-8c8r

Source

https://github.com/advisories/GHSA-hv23-4qp7-8c8r

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-hv23-4qp7-8c8r/GHSA-hv23-4qp7-8c8r.json

JSON Data

https://api.osv.dev/v1/vulns/GHSA-hv23-4qp7-8c8r

Aliases

Published

2026-05-11T21:31:34Z

Modified

2026-06-08T20:31:01Z

Severity

4.0 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N CVSS Calculator
6.3 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N CVSS Calculator

Summary

ninenines cowlib: Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability allows SSE event splitting and injection via unvalidated field values

Details

Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in ninenines cowlib allows SSE event splitting and injection via unvalidated field values.

cow_sse:event/1 in cowlib guards the id and event fields against \n but not against bare \r, and the internal prefix_lines/2 function used for data and comment fields splits only on \n. Because the SSE specification requires decoders to treat \r\n, \r, and \n as equivalent line terminators, an attacker who controls any of these fields can inject additional SSE lines and forge a complete event with an arbitrary event type and data payload on the receiving end. In typical deployments where browser EventSource clients or other SSE consumers dispatch on event.type and render event.data, this enables event splitting, client-side logic manipulation, and stored-XSS-equivalent behaviour when event data is inserted into the DOM.

This issue affects cowlib from 2.6.0.

Database specific

{
    "cwe_ids":  [
        "CWE-93"
    ],
    "github_reviewed":  true,
    "github_reviewed_at":  "2026-05-18T16:47:11Z",
    "nvd_published_at":  "2026-05-11T19:16:25Z",
    "severity":  "MODERATE"
}

References

Affected packages

Hex / cowlib

Package

Name: cowlib
Purl: pkg:hex/cowlib

Affected ranges

Type: SEMVER
Events: Introduced

2.6.0

Fixed

2.16.1

Affected versions

2.*

2.6.0

2.7.0

2.7.1

2.7.2

2.7.3

2.8.0

2.9.0

2.9.1

2.10.0

2.10.1

2.11.0

2.12.0

2.12.1

2.13.0

2.14.0

2.15.0

2.16.0

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-hv23-4qp7-8c8r/GHSA-hv23-4qp7-8c8r.json"