How severe is CVE-2026-33170?

CVE-2026-33170 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-33170 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33170?

CVE-2026-33170 affects Rubyonrails Rails. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-33170?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-33170 have an EU (EUVD) identifier?

Yes. CVE-2026-33170 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-14624.

When was CVE-2026-33170 published?

CVE-2026-33170 was published on 2026-03-24 and last updated on 2026-06-17.

CVE-2026-33170

CVE-2026-33170 is a medium-severity vulnerability in Rubyonrails Rails with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v4: 5.3
EPSS exploit prediction: 0% (25th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-14624
Weakness: CWE-79
Affected product: Rubyonrails Rails
Published: 2026-03-24
Last modified: 2026-06-17

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, `SafeBuffer#%` does not propagate the `@html_unsafe` flag to the newly created buffer. If a `SafeBuffer` is mutated in place (e.g. via `gsub!`) and then formatted with `%` using untrusted arguments, the result incorrectly reports `html_safe? == true`, bypassing ERB auto-escaping and possibly leading to XSS. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.

Frequently asked questions

What is CVE-2026-33170?: 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, `SafeBuffer#%` does not propagate the `@html_unsafe` flag to the newly created buffer. If a `SafeBuffer` is mutated in place (e.g. via `gsub!`) and then formatted with `%` using untrusted arguments, the result incorrectly reports `html_safe? == true`, bypassing ERB auto-escaping and possibly leading to XSS. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.
How severe is CVE-2026-33170?: CVE-2026-33170 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-33170 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33170?: CVE-2026-33170 affects Rubyonrails Rails. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-33170?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-33170 have an EU (EUVD) identifier?: Yes. CVE-2026-33170 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-14624.
When was CVE-2026-33170 published?: CVE-2026-33170 was published on 2026-03-24 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:*

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