How severe is CVE-2019-17021?

CVE-2019-17021 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2019-17021 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-17021?

CVE-2019-17021 primarily affects Mozilla Firefox. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-17021?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2019-17021 published?

CVE-2019-17021 was published on 2020-01-08 and last updated on 2026-06-17.

CVE-2019-17021

CVE-2019-17021 is a medium-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 5.3. 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-362.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 2.6
EPSS exploit prediction: 2% (77th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-362
Affected product: Mozilla Firefox
Published: 2020-01-08
Last modified: 2026-06-17

Description

During the initialization of a new content process, a race condition occurs that can allow a content process to disclose heap addresses from the parent process. *Note: this issue only occurs on Windows. Other operating systems are unaffected.*. This vulnerability affects Firefox ESR < 68.4 and Firefox < 72.

Frequently asked questions

What is CVE-2019-17021?: During the initialization of a new content process, a race condition occurs that can allow a content process to disclose heap addresses from the parent process. *Note: this issue only occurs on Windows. Other operating systems are unaffected.*. This vulnerability affects Firefox ESR < 68.4 and Firefox < 72.
How severe is CVE-2019-17021?: CVE-2019-17021 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2019-17021 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-17021?: CVE-2019-17021 primarily affects Mozilla Firefox. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-17021?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2019-17021 published?: CVE-2019-17021 was published on 2020-01-08 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*

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Other CWE-362 (Race Condition) vulnerabilities

CVE-2022-27626 — Critical (CVSS 10.0): A vulnerability regarding concurrent execution using shared resource with improper synchronization ('Race Condition')…
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