CVE-2026-11525: undici vulnerable to Set-Cookie SameSite attribute downgrade via permissive substring matching
CSIRTS triage
- What
- The vulnerability allows for a downgrade of the Set-Cookie SameSite attribute via permissive substring matching.
- Who is affected
- Deployments using undici.
- Urgency
- Remediation is low urgency as the severity is low and exploitation is not currently active.
- Action
- Update to the latest version of undici.
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Details
Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-11525
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-2026-115250.25% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 16% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-11525 | coverage & exploitation status | NVD · CVE.org |
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