PKCS#7 decode ignores caller output buffer size, writing past buffer bounds

published 2026-06-25 4 mo ago modified 2026-07-25 3 mo ago also EUVD-2026-39556 , GHSA-6q89-vxvr-wgv2 , JLSEC-2026-754

cvss: 5.3; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits: 0; none known

The PKCS#7 decode path ignores the caller-supplied output buffer size (outputSz), allowing decoded content to be written past the bounds of the provided buffer. This affects wolfSSL 5.9.0 and earlier and was fixed in the 5.9.1 release.

Patch / fix

fixed in 2 distros 2 links 1

julia wolfSSL_jll 5.9.2+0
wolfssl wolfssl 5.9.1

debian alpine

wolfssl Debian 12 5.5.4-2+deb12u3
wolfssl Debian 13 5.7.2-0.1+deb13u2

debian advisories DEBIAN-CVE-2026-6681

wolfssl Alpine 3.24 5.9.2-r0

alpine advisories ALPINE-CVE-2026-6681

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

github.com/wolfSSL/wolfssl#10116 pull request

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 4 mo ago (2026-06-26)

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	1.0	CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/U:Clear
CNA	4.0	1.0	CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/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:Clear
NVD	3.1	5.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
OSV	3.1	5.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
julia	wolfSSL_jll	<5.9.2+0	5.9.2+0

Affected products

wolfSSL wolfSSL

Classification

Weakness

CWE-787 Out-of-bounds Write
CWE-120 Buffer Copy without Checking Size of Input

References

github.com /wolfSSL/wolfssl/pull/10116
patch, issue-tracking, web
wolfssl.com /docs/security-vulnerabilities/
vendor-advisory, web
github.com /advisories/GHSA-6q89-vxvr-wgv2
web
nvd.nist.gov /vuln/detail/CVE-2026-6681
web
wolfssl.com /docs/security-vulnerabilities
web

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary