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Fencer Vulns
high 7.5

CVE-2021-28902 json

In function read_yin_container() in libyang <= v1.0.225, it doesn't check whether the value of retval->ext[r] is NULL.

published 2021-05-20 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-15555

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 75%
public exploits
0
none known

Summary

In function read_yin_container() in libyang <= v1.0.225, it doesn't check whether the value of retval->ext[r] is NULL. In some cases, it can be NULL, which leads to the operation of retval->ext[r]->flags that results in a crash.

Patch / fix

  • libyang Debian 14, Debian 13 3.4.2+dfsg-2

debian advisories DEBIAN-CVE-2021-28902

  • libyang SLE Module for Server Applications 15 SP4, SLE Module for Server Applications 15 SP3, openSUSE Leap 15.4 +1 more 1.0.184-150300.3.6.1

suse advisories SUSE-SU-2022:3245-1

  • libyang Alpine 3.13 1.0.184-r1
  • libyang Alpine 3.14 1.0.215-r1

alpine advisories ALPINE-CVE-2021-28902

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

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-2021-28902 updated cvss 7.5

libyang: NULL pointer dereference in read_yin_container()

  • Red Hat Enterprise Linux 8 libyang
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux 9 libyang
    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

1.55% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/CESNET/libyang/issues/1454 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

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.