PatchTheCVECVE-2026-5504: A padding oracle exists in wolfSSL's PKCS7 CBC decryption that could allow an attacker to recover plaintext th
CVE-2026-5504 is a medium-severity flaw (CVSS 5.3) affecting wolfssl. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
A padding oracle exists in wolfSSL's PKCS7 CBC decryption that could allow an attacker to recover plaintext through repeated decryption queries with modified ciphertext. In previous versions of wolfSSL the interior padding bytes are not validated.
Why this priority
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 5.3 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.1% (top 99%) |
| CISA exploited list | No |
| Weakness | CWE-354 |
| Published | 2026-04-09 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-5504?
wolfssl: upgrade to newer than 5.9.0. Exact commands for each OS are on this page.
Is CVE-2026-5504 being exploited?
CVE-2026-5504 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-5504 affect?
CVE-2026-5504 affects wolfssl. Severity is medium (CVSS 5.3). A padding oracle exists in wolfSSL's PKCS7 CBC decryption that could allow an attacker to recover plaintext through repeated decryption queries with modified ciphertext. In previous versions of wolfSSL the interior padding bytes are not val
How urgent is CVE-2026-5504?
Priority 24/100. Remotely exploitable, no login, no user action
Software pages
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