🛡️ CVE-2026-53727 on Debian — ruby-css-parser

⚪ Unknown ✅ No Known Exploit OSV

N/A

CVSS Score

0 Low4 Medium7 High9 Critical10

Description

css_parser is a Ruby CSS parser. From 2.2.0 until 3.0.0, CssParser::Parser#read_remote_file in lib/css_parser/parser.rb, and therefore load_uri! and the @import-following branch of add_block!, issued HTTP and HTTPS requests against any host, port, and URI without a scheme allowlist, host or IP filtering, or protection against link-local, loopback, or RFC-1918 addresses. Location: redirects were followed recursively back into the same function, which also serviced file:// URIs, so a single attacker-controlled HTTP redirect could upgrade the bug from SSRF to arbitrary local file disclosure. Any consumer of css_parser that hands it attacker-influenced CSS together with a base_uri: option is exposed. This issue is fixed in version 3.0.0.

Distribution advisory

This page covers CVE-2026-53727 as tracked by Debian, for the package ruby-css-parser. The fix is available in version 3.0.0-1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality high, integrity none, availability none.

Weakness class

DEBIAN-CVE-2026-53727 is classified as CWE-918: Server-Side Request Forgery (SSRF). The server fetches a URL supplied by the caller, which can be pointed at internal systems it alone can reach.

Affected software

DEBIAN-CVE-2026-53727 is recorded against 1 package.

ruby-css-parser (fixed in 3.0.0-1)

Timeline and source

Published on 17 July 2026 and last revised on 19 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

Details

Severity Unknown

CVSS Score N/A

CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

CWE N/A

Public Exploit ✅ No

Source OSV

Published 2026-07-17

Updated 2026-08-20

Modified 2026-08-19

Fix URL N/A

Affected Packages

Software	From version	Fixed in
ruby-css-parser	—	3.0.0-1

References

ADVISORY https://security-tracker.debian.org/tracker/CVE-2026-53727

🔗 NVD 🔗 Mitre

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