CVE-2026-6291: Bleichenbacher padding oracle in PKCS#7 KTRI RSA PKCS#1 v1.5 decryption
CSIRTS triage
- What
- Bleichenbacher padding oracle vulnerability in PKCS#7 KTRI RSA PKCS#1 v1.5 decryption.
- Who is affected
- Users of OpenSSL that implement PKCS#7 decryption.
- Urgency
- This medium severity issue should be remediated to prevent cryptographic attacks.
- Action
- Update to the latest version of OpenSSL.
AI-assisted analysis generated from the source advisory — verify against the original.
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Details
Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-6291
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-2026-62910.15% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 5% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-6291 | coverage & exploitation status | NVD · CVE.org |
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