CVE-2021-29982

MEDIUMNVD 6.56.5—

6.5

Due to incorrect JIT optimization, we incorrectly interpreted data from the wrong type of object, resulting in the potential leak of a single bit of memory. This vulnerability affects Firefox < 91 and Thunderbird < 91.

CVSS v3: 6.5
EG Score: 6.5(medium)
EPSS: 59.9%
KEV: Not listed

Published

August 17, 2021

Last Modified

November 21, 2024

References (8)

security@mozillahttps://bugzilla.mozilla.org/show_bug.cgi?id=1715318
security@mozillahttps://security.gentoo.org/glsa/202202-03
security@mozillahttps://www.mozilla.org/security/advisories/mfsa2021-33/
security@mozillahttps://www.mozilla.org/security/advisories/mfsa2021-36/
af854a3a-2127-422b-91ae-364da2661108https://bugzilla.mozilla.org/show_bug.cgi?id=1715318
af854a3a-2127-422b-91ae-364da2661108https://security.gentoo.org/glsa/202202-03
af854a3a-2127-422b-91ae-364da2661108https://www.mozilla.org/security/advisories/mfsa2021-33/
af854a3a-2127-422b-91ae-364da2661108https://www.mozilla.org/security/advisories/mfsa2021-36/

Patch Availability(2)

Vendor / Ecosystem	Fixed in / Patch	Released	Source
ubuntu	firefox-mozsymbols (91.0+build2-0ubuntu0.21.04.1) @ hirsute	2026-05-26	ubuntu
ubuntu	thunderbird-locale-id (1:91.5.0+build1-0ubuntu0.20.04.1) @ focal	2026-05-26	ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-772Missing Release of Resource after Effective Lifetime

All Vendor Advisories

(2)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 11× in last 7d / 19× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 11:54 UTCEG score recompute
2026-05-26 11:54 UTCVendor advisory
2026-05-26 11:54 UTCGHSA enrichment
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch

Frequently asked(5)

What is CVE-2021-29982?

CVE-2021-29982 is a medium vulnerability published on August 17, 2021. Due to incorrect JIT optimization, we incorrectly interpreted data from the wrong type of object, resulting in the potential leak of a single bit of memory. This vulnerability affects Firefox < 91 and Thunderbird < 91.

When was CVE-2021-29982 disclosed?

CVE-2021-29982 was first published in the National Vulnerability Database on August 17, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-29982 actively exploited?

CVE-2021-29982 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 59.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-29982?

CVE-2021-29982 has a CVSS v3 base score of 6.5 (NVD).

How do I remediate CVE-2021-29982?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-29982, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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CVE-2021-29982

Published

Last Modified

References (8)

Patch Availability(2)

Weakness Classification(1)

All Vendor Advisories

Data Freshness Timeline

Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-29982?

Same vendor

Same CWE

CVE-2021-29982

📅 Published

🔄 Last Modified

🔗 References (8)

Patch Availability(2)

Weakness Classification(1)

All Vendor Advisories

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-29982?

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Frequently asked(5)

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