CVE-2021-28906

Exp

In function read_yin_leaf() 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.

Published: 2021-05-20 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-28906 is rated High Exploit Risk (65.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.37%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-28906

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-28906

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-21 0.27% 0.37% +0.09%
2 2025-11-18 0.37% 0.27% -0.09%
3 2025-11-13 — 0.37% —

Full EPSS history (13 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-28906

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-28906

OS Trackers for CVE-2021-28906

vendor priority summary link
alpine high CVE-2021-28906: 1 source package rows (libyang); 1 state rows across 1 repos (edge-community); fixed 1, open 0. https://security.alpinelinux.org/vuln/CVE-2021-28906
debian unimportant CVE-2021-28906 unimportant priority: Debian including 2 source packages (libyang, libyang2), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 1. https://security-tracker.debian.org/tracker/CVE-2021-28906
gentoo low CVE-2021-28906: 1 GLSA(s) (202107-54), 1 atom(s) (net-libs/libyang); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-28906
redhat medium — https://access.redhat.com/security/cve/CVE-2021-28906
suse high — https://www.suse.com/security/cve/CVE-2021-28906/
ubuntu low CVE-2021-28906 low priority: Ubuntu including 1 source packages (libyang), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 6, ignored 5, needed 2, not-affected 2, released 1. https://ubuntu.com/security/CVE-2021-28906

Affected software / configurations for CVE-2021-28906

Vendor Product Version Raw CPE
cesnet libyang <= 1.0.225 cpe:2.3:a:cesnet:libyang:*:*:*:*:*:*:*:*

References for CVE-2021-28906

URL Tags
https://github.com/CESNET/libyang/issues/1455 Exploit Issue Tracking Patch Third Party Advisory
https://security.gentoo.org/glsa/202107-54 Third Party Advisory
cvelogic Threat Intelligence