LiveActive security incident?Get immediate response
CVE Record

CVE-2026-2903: skvadrik re2c ast.cc check_and_merge_special_rules null pointer dereference

A flaw has been found in skvadrik re2c up to 4.4. Impacted is the function check_and_merge_special_rules of the file src/parse/ast.cc. This manipulation causes null pointer dereference. The attack can only be executed locally. The exploit has been published and may be used. Patch name: febeb977936f9519a25d9fbd10ff8256358cdb97. It is suggested to install a patch to address this issue.

MediumCVSS 4.8Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2026-2903 is a crash bug in re2c, a developer tool. A local user can trigger a null pointer dereference and cause limited availability impact. It is not described as remote code execution, and the bundle does not show active exploitation.

Executive priority

Treat as a moderate developer-tool availability risk. Prioritize remediation on shared build infrastructure and systems that process externally supplied source or grammar files.

Technical view

skvadrik re2c 4.0 through 4.4 is reported affected in src/parse/ast.cc, function check_and_merge_special_rules. The issue is classified as CWE-404 and CWE-476 with CVSS v4.0 score 4.8, requiring local low-privilege access and affecting availability only.

Likely exposure

Exposure is most likely on developer workstations, build hosts, CI systems, or package pipelines where re2c 4.0-4.4 is installed and locally invoked.

Exploitation context

The source bundle states that an exploit has been published and may be used, but KEV is false and no cited source states active exploitation in the wild.

Researcher notes

Evidence supports a local null pointer dereference in re2c, with public exploit material referenced. The bundle does not identify a fixed release number, active exploitation, or confidentiality/integrity impact.

Mitigation direction

  • Identify all installed re2c versions across developer, build, and CI environments.
  • Apply the referenced patch febeb977936f9519a25d9fbd10ff8256358cdb97 or vendor-provided fixed release.
  • Restrict local access to systems where vulnerable re2c is installed.
  • Avoid processing untrusted re2c inputs until patched.
  • Monitor upstream re2c and distribution advisories for packaged fixes.

Validation and detection

  • Confirm whether re2c versions 4.0, 4.1, 4.2, 4.3, or 4.4 are present.
  • Verify patched builds include commit febeb977936f9519a25d9fbd10ff8256358cdb97 or a vendor equivalent.
  • Check CI images, developer base images, and package manifests for re2c dependencies.
  • Review crash reports or build failures involving re2c parsing paths.
Prepared
Confidence
high
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-404: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-476: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-2903 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Medium
CVSS
4.8 (4.0)
Known Exploited
No
Published

Vector: CVSS: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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

4CVSS vectors
6Timeline events
1ADP providers
8Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: noTechnical Impact: partial

CVSS vector scores

4 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
4.8CVSS 4.0MediumCVSS: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——VulDB
3.3CVSS 3.1LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C1.81.4VulDB
3.3CVSS 3.0LowCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C1.81.4VulDB
1.7CVSS 2.0LowAV:L/AC:L/Au:S/C:N/I:N/A:P/E:POC/RL:OF/RC:C3.12.9VulDB

Vulnerability scoring details

Base CVSS 4.0 score

4.8Medium
CVSS 4.0 vector shape for CVE-2026-2903Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS: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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. Source timelineVulDB

    Advisory disclosed

  2. Source timelineVulDB

    VulDB entry created

  3. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  4. Source timelineVulDB

    VulDB entry last update

  5. CVE publishedCVE Program

    The CVE record was published.

  6. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
skvadrikre2c4.0, 4.1, 4.2, 4.3, 4.4Listed
Weakness

CWE details

CWE-404CWE-476

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-404 · source CWE mapping

Improper Resource Shutdown or Release

Improper Resource Shutdown or Release represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-476 · source CWE mapping

NULL Pointer Dereference

NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs