CVE-2025-27789: Inefficient RexExp complexity in generated code with .replace when transpiling named capturing groups
CSIRTS triage
- What
- Inefficient regular expression complexity in transpiled code when handling .replace operations with named capturing groups.
- Who is affected
- JavaScript/TypeScript applications using transpilers that handle named capturing groups with .replace.
- Urgency
- Medium severity (CVSS 6.2) denial of service via regex complexity; impacts transpilation and runtime performance.
- Action
- Update transpiler to optimize regex complexity for named capturing group replacements.
AI-assisted analysis generated from the source advisory — verify against the original.
Details
Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-27789
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2025-277890.55% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 44% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2025-27789 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- highexploited[UPDATE] [high] Oracle Communications: Multiple vulnerabilitiescert-bund
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