Mistune 3.3.0 before 3.3.4 Quadratic-Time DoS via _process_emphasis_delimiters
CVSS score
8.7
EPSS probability
—
Risk score
0.9
Published
4 h ago
Etkilenen ürün ve sürüm için yayımlanan güvenlik güncellemesini uygulayın.
Impact on My Inventory
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Vulnerability description
DayBreach AI Explanation
Verified against sourcesSources read
2
Source agreement
0/2
Evidence confidence
%44
Short explanation
Mistune from version 3.3.0 before 3.3.4 contains a denial of service vulnerability that allows remote attackers to exhaust CPU resources during emphasis delimiter processing.
This vulnerability enables remote attackers to submit specially crafted small markdown documents to stall workers for seconds and exhaust CPU resources.
What should be done?
- Update Mistune according to vendor advisories
- Review patch commit references
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Chain of evidence and sources
Mistune 3.3.0 ile 3.3.4 sürümleri arasında yer alan yapı, _process_emphasis_delimiters işlevinde O(n²) döngüsüne neden olur.
Saldırganlar, *a_b gibi tekrarlanan kalıplara sahip küçük markdown belgeleri göndererek CPU kaynaklarını tüketebilir.
Yama durumu ve doğrulanmış düzeltmeler mevcuttur.
Show the technical text from the sources
Mistune from 3.3.0 before 3.3.4 contains a denial of service vulnerability that allows remote attackers to exhaust CPU through quadratic-time emphasis delimiter processing. Attackers can submit small markdown documents with repeated patterns like "*a_b" to trigger an O(n²) index-fixup loop, stalling workers for seconds.
CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CWE: CWE-407
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-2026-121437 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 |
|---|---|---|---|---|
| 8.7 | CVSS V40 | HIGH | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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 |
| 8.7 | CVSS V4_0 | HIGH | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N | CVE CNA |
| 7.5 | CVSS V31 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD |
| 7.5 | CVSS V3_1 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | 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-2026-121437 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-2026-121437 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
Similar Vulnerabilities
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