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CVE Record

CVE-2021-29982: Due to incorrect JIT optimization, we incorrectly interpreted data from the wrong type of object, resulting...

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Mozilla issue could let a vulnerable Firefox or Thunderbird process leak one bit of memory because the JIT engine interpreted an object as the wrong type. The public record says Firefox before 91 and Thunderbird before 91 are affected. No source provided shows active exploitation or a CVSS score.

Executive priority

Treat this as routine but time-bound desktop software remediation. The public evidence does not show exploitation, but vulnerable browser and mail clients interact with untrusted content and should not remain below version 91.

Technical view

CVE-2021-29982 is an incorrect JIT optimization/type-confusion style flaw causing data to be read from the wrong object type, with a potential single-bit memory disclosure. The affected products listed are Mozilla Firefox < 91 and Mozilla Thunderbird < 91. Public details in the bundle are limited.

Likely exposure

Exposure is mainly legacy Firefox or Thunderbird installations below version 91, especially endpoints that browse untrusted sites or process untrusted email content. Current supported versions should not be assumed affected from the provided sources.

Exploitation context

CISA KEV status is false, and the supplied sources do not cite active exploitation. The described impact is limited to a potential single-bit memory leak, but JIT memory issues still warrant prompt removal from user-facing desktop software.

Researcher notes

The source bundle provides limited technical detail: incorrect JIT optimization, wrong-object interpretation, and potential single-bit memory disclosure. It does not provide CVSS, CWE, proof of exploitation, or detailed exploit conditions. Avoid expanding impact beyond Firefox < 91 and Thunderbird < 91.

Mitigation direction

  • Upgrade Firefox to version 91 or later, preferably a current supported release.
  • Upgrade Thunderbird to version 91 or later, preferably a current supported release.
  • Follow Mozilla advisory guidance for upstream packages.
  • For Gentoo-managed systems, follow GLSA-202202-03 package guidance.
  • Remove or isolate unsupported legacy Firefox and Thunderbird installations.

Validation and detection

  • Inventory Firefox and Thunderbird versions across managed endpoints.
  • Confirm no Firefox installations remain below version 91.
  • Confirm no Thunderbird installations remain below version 91.
  • Check vulnerability scanner findings against CVE-2021-29982.
  • Verify distro package advisories are remediated where applicable.
Prepared
Confidence
high
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2021-29982 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
5Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
MozillaFirefoxunspecifiedListed
MozillaThunderbirdunspecifiedListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.