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VulnerabilityPublished Updated

CVE-2026-44312: premailer css_parser · Untrusted Functionality Inclusion

Affects premailer css_parserSource CVE Database V5

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Not known to be exploited · CVSS 5.8 Medium : upgrade to 2.1.0 or 1.22.0 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
5.8Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.1.0, 1.22.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade css_parser to 2.1.0 or 1.22.0; css_parser to 1.22.0.

Affected software

ProductAffectedFixed in
premailercss_parserAffected
  • >=2.0.0 <2.1.0
Fixed in
  • 2.1.0
premailercss_parserAffected
  • <1.22.0
Fixed in
  • 1.22.0
RubyGemscss_parserpkg:gem/css_parserOther threatsAffected
  • <1.22.0
Fixed in
  • 1.22.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade css_parser to version 2.1.0 or later, or 1.22.0 or later, where proper HTTPS certificate validation is implemented. No other mitigations are indicated as the vulnerability is fixed in these versions. Patch status is confirmed by the vendor advisory stating the fix is included in these releases.

Description

css_parser is a Ruby CSS parser. Prior to 2.1.0 and 1.22.0, the CSS Parser gem does not validate HTTPS connections, allowing a Man-in-the-Middle (MITM) attacker to inject or modify CSS content when stylesheets are loaded via HTTPS. The connection is established with OpenSSL::SSL::VERIFY_NONE, meaning any HTTPS certificate—even entirely untrusted—will be accepted without validation. This vulnerability is fixed in 2.1.0 and 1.22.0.

References

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