CVE-2026-5778 Integer underflow leads to out-of-bounds access in sniffer ChaCha decrypt path.
An attacker can cause a denial of service in applications using wolfSSL's sniffer feature by sending malformed TLS records that trigger an integer underflow and crash.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-5778?
CVE-2026-5778 is a low-severity vulnerability in Wolfssl Wolfssl, published on 9 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-191
Which versions are affected by CVE-2026-5778?
It affects 1 product.
Products include Wolfssl Wolfssl.
How do I fix CVE-2026-5778?
Upgrade to a fixed version.
Is CVE-2026-5778 being exploited?
There is no known exploitation of CVE-2026-5778 in the wild and no public exploit code.
Other vulnerabilities in Wolfssl Wolfssl
Sources
Also known as DEBIAN-CVE-2026-5778, GHSA-2jvp-h4w4-2vxh, JLSEC-2026-741, UBUNTU-CVE-2026-5778.