CVE-2026-6291: wolfSSL's PKCS#7 EnvelopedData decryption · Bleichenbacher Padding Oracle Vulnerability Exists
Source GCVE Database
Not known to be exploited · CVSS 6.5 Medium.
Data as of 30 Oct 2026, 06:59 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 15% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:NExploitation evidence
Disclosed: evidence found.
CVE published 25 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
AI-suggested
The described fix involves generating a deterministic pseudo-random fake CEK on padding failure and using constant-time operations to ensure uniform error responses, which mitigates the padding oracle. Until an official fix or patch is confirmed, users should monitor vendor advisories for updates.
Description
A Bleichenbacher padding oracle vulnerability exists in wolfSSL's PKCS#7 EnvelopedData decryption when using RSA PKCS#1 v1.5 key transport. The library returned distinguishable error codes depending on whether RSA padding validation failed or the decrypted content was malformed, allowing an attacker to use error responses as a padding oracle to recover the encrypted Content Encryption Key (CEK). The fix involves generating a deterministic pseudo-random fake CEK on padding failure and using constant-time operations to ensure all failure paths produce the same error, preventing information leakage.