Stack buffer overflow in PKCS7 SignedData encoding with custom signed attributes
Summary
| CVE | CVE-2026-0819 |
|---|---|
| State | PUBLISHED |
| Assigner | wolfSSL |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-03-19 17:16:21 UTC |
| Updated | 2026-04-29 18:50:05 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 2.2 LOW from [email protected]
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.000180000 probability, percentile 0.048510000 (date 2026-05-05)
Problem Types: CWE-121 | CWE-787 | CWE-121 CWE-121: Stack-based Buffer Overflow | CWE-787 CWE-787: Out-of-bounds Write
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 2.2 | LOW | 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/C... |
| 4.0 | CNA | CVSS | 2.2 | LOW | 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 |
| 3.1 | [email protected] | Primary | 7.1 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H |
CVSS v4.0 Breakdown
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
NVD Known Affected Configurations (CPE 2.3)
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/wolfSSL/wolfssl/pull/9630 | [email protected] | github.com | Issue Tracking, Patch |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Maor Caplan (en)
Additional Advisory Data
Solutions
CNA: Update to the patched version of wolfSSL. The fix adds proper bounds checking in wc_PKCS7_BuildSignedAttributes() to validate that the number of custom signed attributes does not exceed the available space in the fixed-size signedAttribs array, returning BUFFER_E if the limit is exceeded.
Workarounds
CNA: Ensure that applications using wolfSSL PKCS7 signing functionality validate and limit the number of custom signed attributes (signedAttribsSz) to no more than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default signed attributes enabled. Do not allow untrusted input to control the signedAttribs array or its size.