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Fencer Vulns
medium 4.3

CVE-2020-13131 json

An issue was discovered in Yubico libykpiv before 2.1.0.

published 2020-07-09 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-5407

cvss
4.3
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

An issue was discovered in Yubico libykpiv before 2.1.0. lib/util.c in this library (which is included in yubico-piv-tool) does not properly check embedded length fields during device communication. A malicious PIV token can misreport the returned length fields during RSA key generation. This will cause stack memory to be copied into heap allocated memory that gets returned to the caller. The leaked memory could include PINs, passwords, key material, and other sensitive information depending on the integration. During further processing by the caller, this information could leak across trust boundaries. Note that RSA key generation is triggered by the host and cannot directly be triggered by the token.

Patch / fix

  • yubico libykpiv 2.1.0
  • yubico piv_tool_manager 2.0.0
  • yubico-piv-tool Debian 14, Debian 13, Debian 12 2.1.1-1

debian advisories DEBIAN-CVE-2020-13131

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-13131 updated cvss 4.3

yubico-piv-tool: lib/util.c does not properly check embedded length fields could result in information disclosure

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • blog.inhq.net https://blog.inhq.net/posts/yubico-libykpiv-vuln/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 4.3 CVSS:3.0/AC:L/AV:P/A:N/C:H/I:N/PR:N/S:U/UI:R
NVD 3.1 4.3 CVSS:3.1/AV:P/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CNA 3.0 4.3 CVSS:3.0/AV:P/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
NVD 2.0 1.9 AV:L/AC:M/Au:N/C:P/I:N/A:N

Classification

Weakness

References

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.