Vulnerability · Published Mar 19, 2026 · Assigned by wolfSSL
CVE-2026-0819Stack buffer overflow in PKCS7 SignedData encoding with custom signed attributes
Low 2.2
In plain English
A low-severity stack buffer overflow in wolfSSL from wolfSSL. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 1% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | wolfssl | 5.9.1-r0 | ALPINE-CVE-2026-0819 |
| Alpine:v3.24 | wolfssl | 5.9.0-r0 | ALPINE-CVE-2026-0819 |
| Debian:12 | wolfssl | no fix listed | DEBIAN-CVE-2026-0819 |
| Debian:13 | wolfssl | no fix listed | DEBIAN-CVE-2026-0819 |
| Ubuntu:22.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2026-0819 |
| Ubuntu:24.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2026-0819 |
| Ubuntu:25.10 | wolfssl | no fix listed | UBUNTU-CVE-2026-0819 |
| Ubuntu:26.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2026-0819 |
Affected products (as reported)
Weakness: CWE-121, CWE-787 · Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:U