CVE-2021-29982: Due to incorrect JIT optimization, we incorrectly interpreted data from the wrong type of object, resulting in the potential leak of a singl
Noroxi assessment
Priority: Monitor (action score 26/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 1.1% (FIRST EPSS); higher than 66.2% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
- Fixed version: MozillaFirefox (openSUSE:Leap 15.2) 91.2.0-lp152.2.67.1; MozillaThunderbird (openSUSE:Leap 15.2) 91.4.0-lp152.2.52.1; rust-cbindgen (openSUSE:Leap 15.2) 0.19.0-lp152.2.7.1.
Low priority for now. Upgrade to MozillaFirefox (openSUSE:Leap 15.2) 91.2.0-lp152.2.67.1; MozillaThunderbird (openSUSE:Leap 15.2) 91.4.0-lp152.2.52.1; rust-cbindgen (openSUSE:Leap 15.2) 0.19.0-lp152.2.7.1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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.
- Published
- Aug 17, 2021
- Updated
- Jun 16, 2026
- EPSS
- 1.1% · 66th percentile
- CWE
- CWE-772
Report tools
Action score
26
Monitor
Low priority for now.
- CVSS
- 26 / 40 · 6.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.1%
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| mozilla | firefox | cpe:2.3:a:mozilla:firefox |
| mozilla | thunderbird | cpe:2.3:a:mozilla:thunderbird |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- mozilla firefoxbefore 91.0
- mozilla thunderbirdbefore 91.0
Versions reported by the vendor
Affected version ranges reported by the assigning authority (mozilla). Independent of NVD's CPE analysis and usually ahead of it.
Mozilla Firefox
- unspecified and later · before 91affected
Mozilla Thunderbird
- unspecified and later · before 91affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| openSUSE:Leap 15.2 | MozillaFirefox | before 91.2.0-lp152.2.67.1 | 91.2.0-lp152.2.67.1 |
| openSUSE:Leap 15.2 | MozillaThunderbird | before 91.4.0-lp152.2.52.1 | 91.4.0-lp152.2.52.1 |
| openSUSE:Leap 15.2 | rust-cbindgen | before 0.19.0-lp152.2.7.1 | 0.19.0-lp152.2.7.1 |
| openSUSE:Leap 15.3 | MozillaFirefox | before 91.2.0-8.54.1 | 91.2.0-8.54.1 |
| openSUSE:Leap 15.3 | MozillaFirefox-branding-SLE | before 91-9.5.1 | 91-9.5.1 |
| openSUSE:Leap 15.3 | MozillaThunderbird | before 91.4.0-8.45.2 | 91.4.0-8.45.2 |
| openSUSE:Leap 15.3 | rust-cbindgen | before 0.19.0-1.9.1 | 0.19.0-1.9.1 |
| SUSE:HPE Helion OpenStack 8 | MozillaFirefox | before 91.9.0-112.104.1 | 91.9.0-112.104.1 |
| SUSE:HPE Helion OpenStack 8 | MozillaFirefox | before 91.1.0-112.71.1 | 91.1.0-112.71.1 |
| SUSE:HPE Helion OpenStack 8 | MozillaFirefox-branding-SLE | before 91-35.6.6 | 91-35.6.6 |
| SUSE:Linux Enterprise High Performance Computing 15-ESPOS | MozillaFirefox | before 91.9.0-150000.150.34.1 | 91.9.0-150000.150.34.1 |
| SUSE:Linux Enterprise High Performance Computing 15-ESPOS | MozillaFirefox | before 91.2.0-3.155.2 | 91.2.0-3.155.2 |
| SUSE:Linux Enterprise High Performance Computing 15-ESPOS | MozillaFirefox-branding-SLE | before 91-4.19.1 | 91-4.19.1 |
| SUSE:Linux Enterprise Module for Desktop Applications 15 SP2 | MozillaFirefox | before 91.2.0-8.54.1 | 91.2.0-8.54.1 |
| SUSE:Linux Enterprise Module for Desktop Applications 15 SP2 | MozillaFirefox-branding-SLE | before 91-9.5.1 | 91-9.5.1 |
| SUSE:Linux Enterprise Server 11 SP4-LTSS | MozillaFirefox | before 91.2.0-78.143.1 | 91.2.0-78.143.1 |
| SUSE:Linux Enterprise Server 11 SP4-LTSS | MozillaFirefox | before 78.14.0-78.140.4 | 78.14.0-78.140.4 |
| SUSE:Linux Enterprise Server 11 SP4-LTSS | MozillaFirefox-branding-SLED | before 91-21.18.1 | 91-21.18.1 |
| SUSE:Linux Enterprise Workstation Extension 15 SP2 | MozillaThunderbird | before 91.4.0-8.45.2 | 91.4.0-8.45.2 |
Same product
mozilla: all recordsOther highest-scoring records for the same primary product.
- CVE-2010-3765Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before 3.1.6 and 3.0.x before 3.0.10, and SeaMonkey 2.x befKEV94Now
- CVE-2019-11708Insufficient vetting of parameters passed with the Prompt:Open IPC message between child and parent processes can result in the non-sandboxeKEV87Now
- CVE-2015-4495The PDF reader in Mozilla Firefox before 39.0.3, Firefox ESR 38.x before 38.1.1, and Firefox OS before 2.2 allows remote attackers to bypassKEV86Now
Published before and after this one in the same product
- ← EarlierCVE-2021-29980Aug 17, 2021 · Uninitialized memory in a canvas object could have caused an incorrect free() leading to memory corruption and a potentially exploitable cra35Monitor
- ← EarlierCVE-2021-29981Aug 17, 2021 · An issue present in lowering/register allocation could have led to obscure but deterministic register confusion failures in JITted code that35Monitor
- Later →CVE-2021-29983Aug 17, 2021 · Firefox for Android could get stuck in fullscreen mode and not exit it even after normal interactions that should cause it to exit.26Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| opensuse:MozillaFirefox | 91.2.0-lp152.2.67.1 · openSUSE:Leap 15.2 | Package registry (OSV) |
| opensuse:MozillaFirefox-branding-SLE | 91-9.5.1 · openSUSE:Leap 15.3 | Package registry (OSV) |
| opensuse:MozillaThunderbird | 91.4.0-lp152.2.52.1 · openSUSE:Leap 15.2 | Package registry (OSV) |
| opensuse:rust-cbindgen | 0.19.0-lp152.2.7.1 · openSUSE:Leap 15.2 | Package registry (OSV) |
| suse:MozillaFirefox | 78.14.0-78.140.4 · SUSE:Linux Enterprise Server 11 SP4-LTSS | Package registry (OSV) |
| suse:MozillaFirefox-branding-SLE | 91-35.6.6 · SUSE:HPE Helion OpenStack 8 | Package registry (OSV) |
| suse:MozillaFirefox-branding-SLED | 91-21.18.1 · SUSE:Linux Enterprise Server 11 SP4-LTSS | Package registry (OSV) |
| suse:MozillaThunderbird | 91.4.0-8.45.2 · SUSE:Linux Enterprise Workstation Extension 15 SP2 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- A user must open a link or visit a page.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-772 · Missing Release of Resource after Effective LifetimeCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
Change log
- Fix✗ → ✓
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References
Show all references (2 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.