CVE-2021-41816

medium

Published 2021-11-24 · Modified 2026-02-04

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CVSS v3

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CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v4 NEW

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not yet in upstream

VIR risk

5.5

Description

CGI.escape_html in Ruby before 2.7.5 and 3.x before 3.0.3 has an integer overflow and resultant buffer overflow via a long string on platforms (such as Windows) where size_t and long have different numbers of bytes. This also affects the CGI gem before 0.3.1 for Ruby.

Predictions

Exploit likelihood

30%

Patch ETA

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Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

OS impact

OS	Version	Status	Fixed in
arch		affected
debian	bullseye	fixed	`2.7.4-1+deb11u1`

Package impact

Ecosystem	Package	Vulnerable	Fixed
RubyGems	cgi	`<~> 0.1.0.1`	`~> 0.1.0.1`
RubyGems	cgi	`>=0.3.0,<0.3.1`	`0.3.1`
RubyGems	cgi	`>=0.2.0,<0.2.1`	`0.2.1`
RubyGems	cgi	`<0.1.0.1`	`0.1.0.1`

References

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.