How severe is CVE-2026-61847?

No CVSS score has been assigned to CVE-2026-61847 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-61847?

CVE-2026-61847 affects the following packages: crass (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2026-61847?

Update crass to 1.0.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-61847 is resolved across your whole dependency graph.

How do I detect CVE-2026-61847 in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for crass, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-61847 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-61847 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-61847 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What type of vulnerability is CVE-2026-61847?

CVE-2026-61847 is classified as CWE-674 (CWE-674). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-61847 published, and has it been updated?

CVE-2026-61847 was published on October 29, 2026 and was last updated on October 29, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎 RubyGems

Not in CISA KEV

CVE-2026-61847 — crass

Fix: rgrove/crass@25d78cc

CVE-2026-61847 is a CWE-674 vulnerability in crass. A fix is available for crass — see the affected versions and patch details below.

Crass: A large number of adjacent CSS comments can trigger a SystemStackError

Published

Oct 29, 2026

Updated

Oct 29, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 29, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

💎crass

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

Impact

When the :preserve_comments option is not enabled (which is the default behavior), Crass discards CSS comments by recursively consuming the next token. An attacker who provides a stylesheet containing a very large number of adjacent comments can cause excessive recursion and trigger a SystemStackError.

Patches

This is fixed in Crass 1.0.7, which no longer recurses when discarding comments.

Workarounds

Set the :preserve_comments option to true if this is acceptable to your use case (recursion doesn't occur when comments are preserved).

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`crass`	all versions	1.0.7`bundle update crass --conservative`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for crass, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update crass to 1.0.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-61847 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Impact When the `:preserve_comments` option is not enabled (which is the default behavior), Crass discards CSS comments by recursively consuming the next token. An attacker who provides a stylesheet containing a very large number of adjacent comments can cause excessive recursion and trigger a `SystemStackError`. ### Patches This is fixed in Crass 1.0.7, which no longer recurses when discarding comments. ### Workarounds Set the `:preserve_comments` option to `true` if this is acceptable to your use case (recursion doesn't occur when comments are preserved).

O3 Security · Impact-Aware SCA

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