Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| wolfSSL | wolfSSL | 3.9.10 – ≤ 5.9.1 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 13 | wolfssl | No fix yet | — |
| Debian 12 | wolfssl | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | wolfssl | No fix yet | — |
| Ubuntu 26.04 LTS | wolfssl | No fix yet | — |
| Ubuntu 25.10 | wolfssl | No fix yet | — |
| Ubuntu 24.04 LTS | wolfssl | No fix yet | — |
| Ubuntu 22.04 LTS | wolfssl | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | wolfssl | No fix yet | — |
| Ubuntu 18.04 LTS | wolfssl | No fix yet | — |
| Ubuntu 16.04 LTS | wolfssl | No fix yet | — |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | wolfssl | 5.9.2-r0 | — |