CVE-2026-53727
Ruby css_parser SSRF allowing HTTP(S) requests and possible local file disclosure via redirects.
Is CVE-2026-53727 being exploited?
Not confirmed. CVE-2026-53727 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.36% probability of exploitation in the next 30 days.
How severe is CVE-2026-53727?
CVE-2026-53727 is rated High with a CVSS score of 8.9. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-53727?
Yes. A fix has been recorded for CVE-2026-53727. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-53727 affect?
CVE-2026-53727 affects css_parser gem 2.2.0–<3.0.0, Ruby applications using css_parser with base_uri option. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-53727?
Upgrade to css_parser >=3.0.0; avoid parsing untrusted CSS or validate/sanitize base_uri.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote SSRF: attacker-controlled CSS can trigger HTTP/HTTPS requests to arbitrary hosts/ports and, via redirects, disclose local files.
Patch when possible
- affected< 3.0.0
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.