Mistune before 3.3.3 Denial of Service via Balanced Bracket Link Parsing
CVSS score
6.9
EPSS probability
—
Risk score
0.7
Published
4 h ago
Etkilenen ürün ve sürüm için yayımlanan güvenlik güncellemesini uygulayın.
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Vulnerability description
DayBreach AI Explanation
Verified against sourcesSources read
1
Source agreement
Tam uyum
Evidence confidence
%55
Short explanation
Mistune contains a denial of service vulnerability affecting the InlineParser.parse_link component [S0]. This vulnerability allows attackers to cause quadratic CPU growth by supplying balanced nested brackets [S0].
Attackers can submit crafted Markdown inputs that lead to CPU exhaustion in parsing applications [S0]. This issue can trigger service disruptions in affected applications [S0].
What should be done?
- Update Mistune to an unaffected version [S0].
- Follow vendor advisories to apply remediation steps [S0].
Chain of evidence and sources
Mistune yazılımının 3.3.3 öncesi sürümleri, InlineParser.parse_link içinde bir hizmet dışı bırakma zafiyeti barındırmaktadır [S0].
Saldırganlar, binlerce iç içe ayraç çifti göndererek kuadratik CPU büyümesine neden olabilir [S0].
Show the technical text from the sources
Mistune before 3.3.3 contains a denial of service vulnerability in InlineParser.parse_link that allows attackers to cause quadratic CPU growth by supplying balanced nested brackets. Attackers can submit crafted Markdown with thousands of nested bracket pairs not forming a valid link, triggering repeated _contains_nested_link scans that exhaust CPU in parsing applications.
CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CWE: CWE-400
This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-121438 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
| ID | VENDOR | PRODUCT | ACTION |
|---|---|---|---|
| 1 | lepture | mistune | View |
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 6.9 | CVSS V40 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD |
| 6.9 | CVSS V4_0 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N | CVE CNA |
| 5.3 | CVSS V31 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L | NVD |
| 5.3 | CVSS V3_1 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L | CVE CNA |
Patch and Remediation Guide
Solution & Remediation Advisory
2 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.
Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-121438 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-121438 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
Similar Vulnerabilities
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