CVE-2026-2903Public exploit

Local process crash via empty-rule determinization

Published Feb 22, 2026 · Updated Feb 22, 2026

NULL pointer dereference in re2c 4.0 through 4.4 allows local users to crash the lexer generator with a crafted .re file. For a normal block containing an action but no rules, check_and_merge_special_rules fails to reject the empty grammar, so determinization dereferences a null root TNFA state. The user must be able to run re2c on the crafted local input; the resulting segmentation fault aborts that re2c process without affecting confidentiality or integrity.

CVSS severity3.3
Low
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in re2c 4.0 through 4.4 allows local users to crash the lexer generator with a crafted .re file. For a normal block containing an action but no rules, check_and_merge_special_rules fails to reject the empty grammar, so determinization dereferences a null root TNFA state. The user must be able to run re2c on the crafted local input; the resulting segmentation fault aborts that re2c process without affecting confidentiality or integrity.

The record

CVE
CVE-2026-2903
Published
Feb 22, 2026
Updated
Feb 22, 2026
Vendor
re2c Project
Product
re2c
Classifications
CWE-404, CWE-476
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.0
  2. Affected versionversion=4.1
  3. Affected versionversion=4.2
  4. Affected versionversion=4.3
  5. Affected versionversion=4.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

re2c Project · re2cversion=4.0; version=4.1; version=4.2; version=4.3; version=4.4

Published CVSS scores

1.7VulDBAV:L/AC:L/Au:S/C:N/I:N/A:P
1.9VulDBCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
3.3VulDBCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

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.

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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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-404Improper Resource Shutdown or Release
CWE-476NULL Pointer Dereference

Public exploit references

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

Technologies

Your stack

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Your stack

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