CVE-2026-6291
mediumpriority · track · 26EPSS 0.002 · 15 %ileEUUSEPSS · scored 2026-10-27
Bleichenbacher padding oracle in PKCS#7 KTRI decryption. When decrypting PKCS#7 EnvelopedData using RSA PKCS#1 v1.5 key transport, wolfSSL returned distinguishable error codes depending on whether RSA padding validation failed versus whether the decrypted content was malformed. An attacker able to submit crafted EnvelopedData messages and observe error responses could use this as a padding oracle to incrementally recover the encrypted Content Encryption Key (CEK). The fix generates a deterministic pseudo-random fake CEK on padding failure (via HMAC-SHA256) and proceeds with decryption identically, using constant-time operations throughout, so that all failure paths produce the same error regardless of padding validity.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 2.3–6.5
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (2)
Products and version ranges known to be affected.
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (7)
External citations — patches, advisories, analysis.
- https://github.com/wolfSSL/wolfssl/pull/10203cnnvd
- https://www.wolfssl.com/docs/security-vulnerabilities/cnnvd
- https://www.wolfssl.com/download/Patchcnnvd
- https://github.com/wolfSSL/wolfssl/pull/10203enisa_euvd
- https://www.wolfssl.com/docs/security-vulnerabilities/enisa_euvd
- https://github.com/wolfSSL/wolfssl/pull/10203Issue Trackingnvd
- https://www.wolfssl.com/docs/security-vulnerabilities/Vendor Advisorynvd
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