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Classic Buffer OverflowWeakness · CWE-120

CVE-2024-27280

CRITICAL · 9.8 CVSS v3.1 Published 2024-05-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A buffer-overread issue was discovered in StringIO 3.0.1, as distributed in Ruby 3.0.x through 3.0.6 and 3.1.x through 3.1.4. The ungetbyte and ungetc methods on a StringIO can read past the end of a string, and a subsequent call to StringIO.gets may return the memory value. 3.0.3 is the main fixed version; however, for Ruby 3.0 users, a fixed version is stringio 3.0.1.1, and for Ruby 3.1 users, a fixed version is stringio 3.0.1.2.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Buffer overread vulnerability in StringIO gem's ungetbyte and ungetc methods allows reading past the end of a string buffer. Subsequent calls to StringIO.gets can then return previously stored memory contents, leading to potential sensitive information disclosure.

MitigationUpdate the stringio gem to version 3.0.1.1 for Ruby 3.0.x or 3.0.1.2 for Ruby 3.1.x to patch the buffer overread. Prioritize systems processing untrusted input via StringIO operations.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check if StringIO gem is present in your environment
    Run `gem list stringio` to list the installed StringIO gem and its version
    Affected if StringIO gem is not installed or is installed without a version listed
  2. Verify the StringIO gem version
    Compare the installed version from `gem list stringio` against 3.0.1.1 (Ruby 3.0.x) or 3.0.1.2 (Ruby 3.1.x); versions below these are vulnerable
    Affected if Installed version is lower than 3.0.1.1 for Ruby 3.0.x or lower than 3.0.1.2 for Ruby 3.1.x
  3. Identify if ungetbyte or ungetc methods are called in your code
    Search your codebase for calls to StringIO#ungetbyte or StringIO#ungetc methods, such as `stringio.ungetbyte` or `stringio.ungetc`
    Affected if Your code invokes ungetbyte or ungetc on any StringIO object
  4. Check if gets is called after ungetbyte or ungetc
    Review code paths where StringIO#gets is called after ungetbyte or ungetc operations on the same StringIO object
    Affected if Your code calls gets following ungetbyte or ungetc on the same StringIO instance

You are affected if StringIO gem version is below 3.0.1.1 (Ruby 3.0.x) or below 3.0.1.2 (Ruby 3.1.x) AND your code uses ungetbyte or ungetc followed by gets on StringIO objects processing sensitive data.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update the stringio gem to version 3.0.1.1 for Ruby 3.0.x or 3.0.1.2 for Ruby 3.1.x to patch the buffer overread. Prioritize systems processing untrusted input via StringIO operations.

Recommended fix High confidence

Ruby 3.0.7+ or Ruby 3.1.5+ (or stringio gem 3.0.1.1/3.0.1.2 respectively)

  1. Identify the current Ruby version by running `ruby --version`
  2. If running Ruby 3.0.x (3.0.0 through 3.0.6), upgrade to Ruby 3.0.7 or later
  3. If running Ruby 3.1.x (3.1.0 through 3.1.4), upgrade to Ruby 3.1.5 or later
  4. For users who cannot upgrade Ruby entirely, update the stringio gem separately: run `gem install stringio -v 3.0.1.1` for Ruby 3.0 users, or `gem install stringio -v 3.0.1.2` for Ruby 3.1 users
  5. Verify the fix by running `ruby -e "require 'stringio'; puts StringIO::VERSION"` to confirm the stringio version
  6. Test that the vulnerability is resolved by ensuring StringIO.gets no longer returns memory contents after ungetbyte/ungetc operations
Caveat Minor - upgrading Ruby minor versions may introduce subtle language changes; verify application compatibility in a staging environment before production deployment

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,390
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-27280 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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