CVE-2026-0819 Stack buffer overflow in PKCS7 SignedData encoding with custom signed attributes
Stack buffer overflow in wolfSSL PKCS7 encoding allows code execution or DoS if applications allow untrusted input to control signed attribute sizes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-0819?
CVE-2026-0819 is a low-severity memory corruption vulnerability in Wolfssl Wolfssl, published on 19 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
A stack buffer overflow vulnerability exists in wolfSSL's PKCS7 SignedData encoding functionality. In wc_PKCS7_BuildSignedAttributes(), when adding custom signed attributes, the code passes an incorrect capacity value (esd->signedAttribsCount) to EncodeAttributes() instead of the remaining available space in the fixed-size signedAttribs[7] array. When an application sets pkcs7->signedAttribsSz to a value greater than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default attributes already added, EncodeAttributes() writes beyond the array bounds, causing stack memory corruption. In WOLFSSL_SMALL_STACK builds, this becomes heap corruption. Exploitation requires an application that allows untrusted input to control the signedAttribs array size when calling wc_PKCS7_EncodeSignedData() or related signing functions.
Which versions are affected by CVE-2026-0819?
It affects 1 product.
Products include Wolfssl Wolfssl.
How do I fix CVE-2026-0819?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-0819 being exploited?
There is no known exploitation of CVE-2026-0819 in the wild and no public exploit code.
Other vulnerabilities in Wolfssl Wolfssl
Sources
Also known as DEBIAN-CVE-2026-0819, GHSA-3cr6-hpf3-2hmg, JLSEC-2026-691, UBUNTU-CVE-2026-0819.