How severe is CVE-2021-24044?

CVE-2021-24044 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-2021-24044 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-24044?

CVE-2021-24044 affects Facebook Hermes. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-24044?

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-2021-24044 published?

CVE-2021-24044 was published on 2022-01-15 and last updated on 2026-06-17.

CVE-2021-24044

CVE-2021-24044 is a critical-severity vulnerability in Facebook Hermes 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-843.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (66th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-843
Affected product: Facebook Hermes
Published: 2022-01-15
Last modified: 2026-06-17

Description

By passing invalid javascript code where await and yield were called upon non-async and non-generator getter/setter functions, Hermes would invoke generator functions and error out on invalid await/yield positions. This could result in segmentation fault as a consequence of type confusion error, with a low chance of RCE. This issue affects Hermes versions prior to v0.10.0.

Frequently asked questions

What is CVE-2021-24044?: By passing invalid javascript code where await and yield were called upon non-async and non-generator getter/setter functions, Hermes would invoke generator functions and error out on invalid await/yield positions. This could result in segmentation fault as a consequence of type confusion error, with a low chance of RCE. This issue affects Hermes versions prior to v0.10.0.
How severe is CVE-2021-24044?: CVE-2021-24044 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-2021-24044 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-24044?: CVE-2021-24044 affects Facebook Hermes. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-24044?: 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-2021-24044 published?: CVE-2021-24044 was published on 2022-01-15 and last updated on 2026-06-17.

References

https://www.facebook.com/security/advisories/cve-2021-24044

Affected products (1)

cpe:2.3:a:facebook:hermes:*:*:*:*:*:*:*:*

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