How severe is CVE-2021-31826?

CVE-2021-31826 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-31826 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-31826?

CVE-2021-31826 affects Shibboleth Service Provider. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-31826?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-31826 published?

CVE-2021-31826 was published on 2021-04-27 and last updated on 2026-06-17.

CVE-2021-31826

CVE-2021-31826 is a high-severity vulnerability in Shibboleth Service Provider with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-476.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (78th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Shibboleth Service Provider
Published: 2021-04-27
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-31826?: 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.
How severe is CVE-2021-31826?: CVE-2021-31826 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-31826 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-31826?: CVE-2021-31826 affects Shibboleth Service Provider. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-31826?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-31826 published?: CVE-2021-31826 was published on 2021-04-27 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:shibboleth:service_provider:*:*:*:*:*:*:*:*

More vulnerabilities in Shibboleth Service Provider

CVE-2017-16852 — High (CVSS 8.1): shibsp/metadata/DynamicMetadataProvider.cpp in the Dynamic MetadataProvider plugin in Shibboleth Service Provider…
CVE-2019-19191 — High (CVSS 7.8): Shibboleth Service Provider (SP) 3.x before 3.1.0 shipped a spec file that calls chown on files in a directory…
CVE-2010-2450 — High (CVSS 7.5): The keygen.sh script in Shibboleth SP 2.0 (located in /usr/local/etc/shibboleth by default) uses OpenSSL to create a…
CVE-2023-22947 — High (CVSS 7.3): Insecure folder permissions in the Windows installation path of Shibboleth Service Provider (SP) before 3.4.1 allow an…
CVE-2021-28963 — Medium (CVSS 5.3): Shibboleth Service Provider before 3.2.1 allows content injection because template generation uses attacker-controlled…
CVE-2015-2684 — Medium (CVSS 4.0): Shibboleth Service Provider (SP) before 2.5.4 allows remote authenticated users to cause a denial of service (crash)…

All CVEs affecting Shibboleth Service Provider →

Other CWE-476 (NULL Pointer Dereference) vulnerabilities

CVE-2022-36648 — Critical (CVSS 10.0): The hardware emulation in the of_dpa_cmd_add_l2_flood of rocker device model in QEMU, as used in 7.0.0 and earlier,…
CVE-2020-14500 — Critical (CVSS 10.0): Secomea GateManager all versions prior to 9.2c, An attacker can send a negative value and overwrite arbitrary data.
CVE-2010-2495 — Critical (CVSS 10.0): The pppol2tp_xmit function in drivers/net/pppol2tp.c in the L2TP implementation in the Linux kernel before 2.6.34 does…
CVE-2026-46195 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: client: validate dacloffset before building…
CVE-2026-31657 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: batman-adv: hold claim backbone gateways by…
CVE-2026-31436 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: dmaengine: idxd: fix possible wrong descriptor…

Browse all CWE-476 (NULL Pointer Dereference) vulnerabilities →