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Fencer Vulns
high 7.5

CVE-2021-28903 json

A stack overflow in libyang <= v1.0.225 can cause a denial of service through function lyxml_parse_mem().

published 2021-05-20 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-15556

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.4%
EPSS 2.4% chance of exploitation in 30 days, percentile 84%
public exploits
0
none known

Summary

A stack overflow in libyang <= v1.0.225 can cause a denial of service through function lyxml_parse_mem(). lyxml_parse_elem() function will be called recursively, which will consume stack space and lead to crash.

Patch / fix

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

debian advisories DEBIAN-CVE-2021-28903

  • 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-2021-28903

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-2021-28903 updated cvss 7.5

libyang: recursive call to lyxml_parse_mem() lead to crash

  • 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

2.43% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/CESNET/libyang/issues/1453 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.