CVE-2021-29982

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

Score 6.5 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
6.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 1%CVSS: 6.5Exploit: NoneExposed: 0

A fix is available — apply it.

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)
EG Risk
34(Track)
EG Risk 34/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity65% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
62.9%
KEV
Not listed

Published

August 17, 2021

Last Modified

November 21, 2024

References (8)

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntufirefox-mozsymbols (91.0+build2-0ubuntu0.21.04.1) @ hirsute2026-05-26ubuntu
ubuntuthunderbird-locale-id (1:91.5.0+build1-0ubuntu0.20.04.1) @ focal2026-05-26ubuntu

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.

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 13× in last 7d / 49× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 14:16 UTCEPSS rescore
  2. 2026-07-23 02:00 UTCEG score recompute
  3. 2026-07-22 22:47 UTCEG score recompute
  4. 2026-07-22 14:06 UTCEPSS rescore
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  1. 2026-07-07 13:43 UTCEPSS rescore
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  42. 2026-06-11 13:58 UTCEPSS rescore
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  45. 2026-06-08 14:15 UTCEPSS rescore
  46. 2026-06-07 15:23 UTCEPSS rescore
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  48. 2026-06-06 13:46 UTCEPSS rescore
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  70. 2026-05-26 13:42 UTCEPSS rescore
  71. 2026-05-26 11:54 UTCEG score recompute
  72. 2026-05-26 11:54 UTCVendor advisory
  73. 2026-05-26 11:54 UTCGHSA enrichment
  74. 2026-05-26 07:17 UTCEPSS rescore
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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 62.9% 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.

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