How severe is CVE-2021-36357?

CVE-2021-36357 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-36357 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-36357?

CVE-2021-36357 affects Openpowerfoundation Skiboot. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-36357?

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

When was CVE-2021-36357 published?

CVE-2021-36357 was published on 2021-10-22 and last updated on 2026-06-17.

CVE-2021-36357

CVE-2021-36357 is a critical-severity vulnerability in Openpowerfoundation Skiboot with a CVSS 3.x base score of 9.8. 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-681.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (63rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-681
Affected product: Openpowerfoundation Skiboot
Published: 2021-10-22
Last modified: 2026-06-17

Description

An issue was discovered in OpenPOWER 2.6 firmware. unpack_timestamp() calls le32_to_cpu() for endian conversion of a uint16_t "year" value, resulting in a type mismatch that can truncate a higher integer value to a smaller one, and bypass a timestamp check. The fix is to use the right endian conversion function.

Frequently asked questions

What is CVE-2021-36357?: An issue was discovered in OpenPOWER 2.6 firmware. unpack_timestamp() calls le32_to_cpu() for endian conversion of a uint16_t "year" value, resulting in a type mismatch that can truncate a higher integer value to a smaller one, and bypass a timestamp check. The fix is to use the right endian conversion function.
How severe is CVE-2021-36357?: CVE-2021-36357 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-36357 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-36357?: CVE-2021-36357 affects Openpowerfoundation Skiboot. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-36357?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-36357 published?: CVE-2021-36357 was published on 2021-10-22 and last updated on 2026-06-17.

References

https://github.com/open-power/skiboot/commit/5be38b672c1410e2f10acd3ad2eecfdc81d5daf7

Affected products (1)

cpe:2.3:o:openpowerfoundation:skiboot:2.6:*:*:*:*:*:*:*

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