How severe is CVE-2026-5504?

CVE-2026-5504 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2026-5504 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-5504?

CVE-2026-5504 affects Wolfssl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-5504?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-5504 have an EU (EUVD) identifier?

Yes. CVE-2026-5504 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21235.

When was CVE-2026-5504 published?

CVE-2026-5504 was published on 2026-04-09 and last updated on 2026-06-17.

CVE-2026-5504

CVE-2026-5504 is a medium-severity vulnerability in Wolfssl with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-354.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v4: 6.3
EPSS exploit prediction: 0% (2nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-21235
Weakness: CWE-354
Affected product: Wolfssl
Published: 2026-04-09
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-5504?: 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.
How severe is CVE-2026-5504?: CVE-2026-5504 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2026-5504 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-5504?: CVE-2026-5504 affects Wolfssl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-5504?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-5504 have an EU (EUVD) identifier?: Yes. CVE-2026-5504 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21235.
When was CVE-2026-5504 published?: CVE-2026-5504 was published on 2026-04-09 and last updated on 2026-06-17.

References

https://github.com/wolfSSL/wolfssl/pull/10088

Affected products (1)

cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*

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