Vulnerability in Opensc
CVE-2025-66038
OpenSC is an open source smart card tools and middleware. Prior to version 0.27.0, sc_compacttlv_find_tag searches a compact-TLV buffer for a given tag. In compact-TLV, a single byte encodes the tag (high nibble) and value length (low nibble). With a 1-byte buffer {0x0A}, the encoded element claims tag=0 and length=10 but no value bytes follow. Calling sc_compacttlv_find_tag with search tag 0x00 returns a pointer equal to buf+1 and outlen=10 without verifying that the claimed value length fits within the remaining buffer. In cases where the sc_compacttlv_find_tag is provided untrusted data (such as being read from cards/files), attackers may be able to influence it to return out-of-bounds pointers leading to downstream memory corruption when subsequent code tries to dereference the pointer. This issue has been patched in version 0.27.0.
EPSS: 0.003 (20.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 3.9 (Low). Vector: CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L.
Affected products
- Opensc — versions < 0.27.0
- Opensc_project Opensc
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC, Vendor Advisory)
Frequently asked questions
- What is CVE-2025-66038?
- CVE-2025-66038 is a low-severity vulnerability in Opensc, classified under Buffer Over-read. CVSS score: 3.9/10. Published 2026-03-30.
- How severe is CVE-2025-66038?
- Low severity. CVSS v3 base score is 3.9 out of 10.