How severe is CVE-2026-5778?

CVE-2026-5778 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-5778 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-5778?

CVE-2026-5778 affects Wolfssl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-5778?

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

Does CVE-2026-5778 have an EU (EUVD) identifier?

Yes. CVE-2026-5778 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21220.

When was CVE-2026-5778 published?

CVE-2026-5778 was published on 2026-04-09 and last updated on 2026-06-17.

CVE-2026-5778

CVE-2026-5778 is a medium-severity vulnerability in Wolfssl with a CVSS 3.x base score of 6.5. 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-191.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 2.1
EPSS exploit prediction: 0% (13th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-21220
Weakness: CWE-191
Affected product: Wolfssl
Published: 2026-04-09
Last modified: 2026-06-17

Description

Integer underflow in wolfSSL packet sniffer <= 5.9.0 allows an attacker to cause a program crash in the AEAD decryption path by injecting a TLS record shorter than the explicit IV plus authentication tag into traffic inspected by ssl_DecodePacket. The underflow wraps a 16-bit length to a large value that is passed to AEAD decryption routines, causing a large out-of-bounds read and crash. An unauthenticated attacker can trigger this remotely via malformed TLS Application Data records.

Frequently asked questions

What is CVE-2026-5778?: Integer underflow in wolfSSL packet sniffer <= 5.9.0 allows an attacker to cause a program crash in the AEAD decryption path by injecting a TLS record shorter than the explicit IV plus authentication tag into traffic inspected by ssl_DecodePacket. The underflow wraps a 16-bit length to a large value that is passed to AEAD decryption routines, causing a large out-of-bounds read and crash. An unauthenticated attacker can trigger this remotely via malformed TLS Application Data records.
How severe is CVE-2026-5778?: CVE-2026-5778 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-5778 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-5778?: CVE-2026-5778 affects Wolfssl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-5778?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-5778 have an EU (EUVD) identifier?: Yes. CVE-2026-5778 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21220.
When was CVE-2026-5778 published?: CVE-2026-5778 was published on 2026-04-09 and last updated on 2026-06-17.

References

https://github.com/wolfSSL/wolfssl/pull/10125

Affected products (1)

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

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