CVE-2026-53727

HIGHNVD 8.68.6—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.6 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 71% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
8.6EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.6Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
8.6
EG Score
8.6(medium)
EG Risk
55(Track)
EG Risk 55/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity86% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
29%
KEV
Not listed

Published

July 9, 2026

Last Modified

August 18, 2026

Advisory Details (3)

Auto-updated Jul 17, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github.
github Patch Available🟡 PoC Available

SSRF and Local File Disclosure in `CssParser::Parser#read_remote_file` · Advisory · premailer/css_parser · GitHub

https://github.com/premailer/css_parser/security/advisories/GHSA-9pmc-p236-855h
github_commit

commit e0a151458b2a (premailer/css_parser)

Fix landed in premailer/css_parser commit e0a151458b2a — awaiting tagged release

https://github.com/premailer/css_parser/commit/e0a151458b2a801ae265ba420862ef8b1127b3ae
github_commit

commit 7d2ddf0189cd (premailer/css_parser)

Fix landed in premailer/css_parser commit 7d2ddf0189cd — awaiting tagged release

https://github.com/premailer/css_parser/commit/7d2ddf0189cd54b54f378f59daefa10cb036e476

Vendor Advisories for CVE-2026-53727(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
ruby-css-parser1.16.0-1 ... 3.0.0-1 (8 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
ruby-css-parser1.16.0-1 ... 3.0.0-1 (8 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
ruby-css-parser1.19.0-1 ... 3.0.0-1 (6 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
ruby-css-parser1.19.0-1, 1.21.1-1, 2.0.0-1, 2.1.0-13.0.0-1—
RubyGems(1)
PackageVulnerable rangeFixed inDependents
css_parser0.9.0 ... 2.2.0 (64 versions)3.0.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 56× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-30 06:56 UTCEG score recompute
  2. 2026-08-30 01:22 UTCEPSS rescore
  3. 2026-08-28 21:41 UTCEPSS rescore
  4. 2026-08-27 21:46 UTCEG score recompute
  5. 2026-08-27 14:25 UTCEPSS rescore
  6. 2026-08-27 01:10 UTCEG score recompute
  7. 2026-08-26 14:46 UTCEPSS rescore
  8. 2026-08-26 03:53 UTCEG score recompute
  9. 2026-08-25 13:49 UTCEPSS rescore
  10. 2026-08-24 23:11 UTCEG score recompute
  11. 2026-08-24 10:14 UTCEG score recompute
  12. 2026-08-23 08:18 UTCEG score recompute
  13. 2026-08-23 00:19 UTCEPSS rescore
  14. 2026-08-22 06:23 UTCEG score recompute
  15. 2026-08-21 23:49 UTCEPSS rescore
  16. 2026-08-21 04:16 UTCEG score recompute
  17. 2026-08-20 22:55 UTCEPSS rescore
  18. 2026-08-20 01:49 UTCEG score recompute
  19. 2026-08-19 17:04 UTCEPSS rescore
  20. 2026-08-18 15:39 UTCEG score recompute▼ 0.30
  21. 2026-08-18 15:39 UTCNVD updateCVSS v3 → 8.6
  22. 2026-08-18 13:48 UTCEPSS rescore
  23. 2026-08-18 02:55 UTCEG score recompute
  24. 2026-08-17 13:47 UTCEPSS rescore
  25. 2026-08-17 00:05 UTCEG score recompute
Show 56 more
  1. 2026-08-16 14:56 UTCEPSS rescore
  2. 2026-08-16 11:08 UTCEG score recompute
  3. 2026-08-16 02:14 UTCEPSS rescore
  4. 2026-08-15 09:13 UTCEG score recompute
  5. 2026-08-15 01:30 UTCEPSS rescore
  6. 2026-08-14 07:18 UTCEG score recompute
  7. 2026-08-13 22:00 UTCEPSS rescore
  8. 2026-08-12 16:21 UTCEG score recompute
  9. 2026-08-12 13:51 UTCEPSS rescore
  10. 2026-08-11 14:26 UTCEG score recompute
  11. 2026-08-11 01:27 UTCEG score recompute
  12. 2026-08-11 00:00 UTCEPSS rescore
  13. 2026-08-09 23:28 UTCEG score recompute
  14. 2026-08-09 13:46 UTCEPSS rescore
  15. 2026-08-08 21:34 UTCEG score recompute
  16. 2026-08-08 16:37 UTCEPSS rescore
  17. 2026-08-07 19:40 UTCEG score recompute
  18. 2026-08-06 17:45 UTCEG score recompute
  19. 2026-08-06 13:47 UTCEPSS rescore
  20. 2026-08-06 04:47 UTCEG score recompute
  21. 2026-08-05 19:17 UTCEPSS rescore
  22. 2026-08-05 02:36 UTCEG score recompute
  23. 2026-08-04 15:10 UTCEPSS rescore
  24. 2026-08-04 13:38 UTCEG score recompute
  25. 2026-08-04 10:39 UTCEPSS rescore
  26. 2026-08-03 22:33 UTCEG score recompute
  27. 2026-08-03 10:36 UTCEPSS rescore
  28. 2026-08-02 07:39 UTCEG score recompute
  29. 2026-08-02 02:27 UTCEPSS rescore
  30. 2026-08-01 05:43 UTCEG score recompute
  31. 2026-08-01 04:16 UTCEPSS rescore
  32. 2026-07-31 03:42 UTCEG score recompute
  33. 2026-07-30 16:28 UTCEPSS rescore
  34. 2026-07-30 14:45 UTCEG score recompute
  35. 2026-07-30 01:44 UTCEG score recompute
  36. 2026-07-30 01:30 UTCEPSS rescore
  37. 2026-07-28 23:39 UTCEG score recompute
  38. 2026-07-28 15:37 UTCEPSS rescore
  39. 2026-07-27 20:53 UTCEG score recompute
  40. 2026-07-26 18:28 UTCEG score recompute
  41. 2026-07-26 14:54 UTCEPSS rescore
  42. 2026-07-26 05:07 UTCEG score recompute
  43. 2026-07-25 14:18 UTCEPSS rescore
  44. 2026-07-24 14:18 UTCEPSS rescore
  45. 2026-07-23 14:18 UTCEPSS rescore
  46. 2026-07-23 03:19 UTCEG score recompute
  47. 2026-07-22 14:08 UTCEPSS rescore
  48. 2026-07-21 15:25 UTCEPSS rescore
  49. 2026-07-20 17:08 UTCEPSS rescore
  50. 2026-07-19 14:31 UTCEPSS rescore
  51. 2026-07-19 14:31 UTCEPSS rescore
  52. 2026-07-19 03:42 UTCEG score recompute
  53. 2026-07-19 02:29 UTCEPSS rescore
  54. 2026-07-17 20:35 UTCEG score recompute▲ 8.90
  55. 2026-07-17 20:34 UTCMITRE cvelistV5CVSS v3 → 8.9 · CVSS v4 → 8.9
  56. 2026-07-09 13:45 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-53727?
CVE-2026-53727 is a high vulnerability published on July 9, 2026. cssparser is a Ruby CSS parser. From 2.2.0 until 3.0.0, CssParser::Parser#readremotefile in lib/cssparser/parser.rb, and therefore loaduri! and the @import-following branch of addblock!, issued HTTP and HTTPS requests against any host, port, and URI without a scheme allowlist, host or IP filtering,…
When was CVE-2026-53727 disclosed?
CVE-2026-53727 was first published in the National Vulnerability Database on July 9, 2026, with the most recent update on August 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-53727 actively exploited?
CVE-2026-53727 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 70.7% of all scored CVEs.
What is the CVSS score of CVE-2026-53727?
CVE-2026-53727 has a CVSS v3 base score of 8.6 (NVD).
How do I remediate CVE-2026-53727?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-53727, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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