CVE-2021-31826

Exp

Shibboleth Service Provider 3.x before 3.2.2 is prone to a NULL pointer dereference flaw involving the session recovery feature. The flaw is exploitable (for a daemon crash) on systems not using this feature if a crafted cookie is supplied.

Published: 2021-04-27 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-31826 is rated High Exploit Risk (72.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.00%). 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-2021-31826

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

Exploit prediction scoring system (EPSS) score for CVE-2021-31826

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 2026-06-15 1.48% 2.00% +0.52%
2 2025-11-21 0.85% 1.48% +0.62%
3 2025-11-18 — 0.85% —

Full EPSS history (16 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31826

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-2021-31826

OS Trackers for CVE-2021-31826

vendor priority summary link
debian not yet assigned CVE-2021-31826 not yet assigned priority: Debian including 1 source packages (shibboleth-sp), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-31826
suse medium CVE-2021-31826 severity moderate: SUSE including 6 source package names (libshibsp-lite6, libshibsp-lite7, libshibsp6, libshibsp7, shibboleth-sp, shibboleth-sp-devel), 83 product×package rows across 31 product lines (HPE Helion OpenStack 8, SUSE CaaS Platform 4.0, … (31 product lines)): Known Not Affected 83. https://www.suse.com/security/cve/CVE-2021-31826/
ubuntu medium CVE-2021-31826 medium priority: Ubuntu including 1 source packages (shibboleth-sp), 9 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): DNE 3, ignored 2, not-affected 2, released 2. https://ubuntu.com/security/CVE-2021-31826

Affected software / configurations for CVE-2021-31826

Vendor Product Version Raw CPE
shibboleth service_provider >= 3.0.0, < 3.2.2 cpe:2.3:a:shibboleth:service_provider:*:*:*:*:*:*:*:*

References for CVE-2021-31826

cvelogic Threat Intelligence