CVE-2018-21232Public exploit

Process crash via uncontrolled fixed-tag recursion

Published Apr 29, 2020 · Updated Aug 5, 2024

Uncontrolled recursion in re2c before 2.0 allows local users to crash the process by supplying a crafted lexer specification. The find_fixed_tags routine recursively processes fixed-tag structures without a depth bound, consuming the process stack until it overflows. A user must cause re2c to process the input; the published reproduction used a 256 KB stack and ended in a segmentation-fault crash.

CVSS severity5.5
Medium
EPSS probability1.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Uncontrolled recursion in re2c before 2.0 allows local users to crash the process by supplying a crafted lexer specification. The find_fixed_tags routine recursively processes fixed-tag structures without a depth bound, consuming the process stack until it overflows. A user must cause re2c to process the input; the published reproduction used a 256 KB stack and ended in a segmentation-fault crash.

The record

CVE
CVE-2018-21232
Published
Apr 29, 2020
Updated
Aug 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-674, T1499
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 29, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-674Uncontrolled Recursion
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo