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VulnerabilityPublished

CVE-2026-33176: rails activesupport · Uncontrolled Resource Consumption

Affects rails activesupportSource CVE Database V5

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Not known to be exploited · CVSS 6.6 Medium · fixed in 8.1.2.1 : update rails activesupport when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
6.6Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.8% chance of exploitation in 30 days – higher than 58% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 8.1.2.1, 8.0.4.1, 7.2.3.1
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 23 Mar 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 activesupport to 8.1.2.1, 8.0.4.1 or 7.2.3.1; activesupport to 7.2.3.1.

Affected software

ProductAffectedFixed in
railsactivesupportAffected
  • >=8.1.0.beta1 <8.1.2.1
Fixed in
  • 8.1.2.1
railsactivesupportAffected
  • >=8.0.0.beta1 <8.0.4.1
Fixed in
  • 8.0.4.1
railsactivesupportAffected
  • <7.2.3.1
Fixed in
  • 7.2.3.1
RubyGemsactivesupportpkg:gem/activesupportOther threatsAffected
  • <7.2.3.1
Fixed in
  • 7.2.3.1

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

AI-suggested

To mitigate CVE-2026-33176, organizations should immediately upgrade Rails Active Support to versions 8.1.2.1, 8.0.4.1, or 7.2.3.1 or later, where the vulnerability is patched. Additionally, developers should implement input validation and sanitization to reject or limit numeric inputs with excessively large scientific notation before they reach the number helpers. Rate limiting and web application firewalls (WAFs) can be configured to detect and block suspicious payloads containing large scientific notation strings. Monitoring application performance and resource usage can help identify potential exploitation attempts early. For legacy systems where immediate upgrade is not feasible, consider isolating vulnerable components, applying strict input filtering at the application or network edge, and employing resource quotas to prevent resource exhaustion. Regularly review and update dependencies to minimize exposure to similar vulnerabilities.

Description

Active Support is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, Active Support number helpers accept strings containing scientific notation (e.g. `1e10000`), which `BigDecimal` expands into extremely large decimal representations. This can cause excessive memory allocation and CPU consumption when the expanded number is formatted, possibly resulting in a DoS vulnerability. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.

References

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