Buffer Over-read Affecting opensc package, versions <0.27.0~rc1-1


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.28% (20th percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-OPENSC-15886481
  • published4 Apr 2026
  • disclosed30 Mar 2026

Introduced: 30 Mar 2026

CVE-2025-66038  (opens in a new tab)
CWE-126  (opens in a new tab)

How to fix?

Upgrade Debian:unstable opensc to version 0.27.0~rc1-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream opensc package and not the opensc package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1