JIT miscompilation in the JavaScript Engine: JIT component
JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
- BDU:2026-04809
- ALSA-2026:5930
- ALSA-2026:5931
- ALSA-2026:5932
- ALSA-2026:6188
- ALSA-2026:6342
- ALSA-2026:6917
- DLA-4510-1
- DLA-4511-1
- DSA-6178-1
- DSA-6179-1
- openSUSE-SU-2026:10413-1
- openSUSE-SU-2026:10447-1
- openSUSE-SU-2026:10458-1
- openSUSE-SU-2026:20439-1
- RHSA-2026:5930
- RHSA-2026:5931
- RHSA-2026:5932
- RHSA-2026:6188
- RHSA-2026:6342
- Published
- Mar 24, 2026
- Updated
- Jul 15, 2026
- EPSS
- 0.8% · 53th percentile
- CWE
- CWE-843
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Report tools
Action score
39
Monitor
Low priority for now.
- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.8%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| mozilla | firefox | cpe:2.3:a:mozilla:firefox |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- mozilla firefoxbefore 115.34.0
- mozilla firefoxbefore 149.0
- mozilla firefox128.0 and later · before 140.9.0
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
- 115.34 and later · up to and including 115.*not affected · rpm
- 140.9 and later · up to and including 140.*not affected · rpm
- 149 and laternot affected · rpm
Mozilla Thunderbird
- 140.9 and later · up to and including 140.*not affected · rpm
- 149 and laternot affected · rpm
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:10 | firefox | before 140.9.0-1.el10_1 | 140.9.0-1.el10_1 |
| AlmaLinux:10 | thunderbird | before 140.9.0-1.el10_1.alma.1 | 140.9.0-1.el10_1.alma.1 |
| AlmaLinux:8 | firefox | before 140.9.0-1.el8_10.alma.1 | 140.9.0-1.el8_10.alma.1 |
| AlmaLinux:8 | thunderbird | before 140.9.0-1.el8_10.alma.1 | 140.9.0-1.el8_10.alma.1 |
| AlmaLinux:9 | firefox | before 140.9.0-1.el9_7.alma.1 | 140.9.0-1.el9_7.alma.1 |
| AlmaLinux:9 | firefox-x11 | before 140.9.0-1.el9_7.alma.1 | 140.9.0-1.el9_7.alma.1 |
| AlmaLinux:9 | thunderbird | before 140.9.0-1.el9_7.alma.1 | 140.9.0-1.el9_7.alma.1 |
| Debian:11 | firefox-esr | before 140.9.0esr-1~deb11u1 | 140.9.0esr-1~deb11u1 |
| Debian:11 | thunderbird | before 1:140.9.0esr-1~deb11u1 | 1:140.9.0esr-1~deb11u1 |
| Debian:12 | firefox-esr | before 140.9.0esr-1~deb12u1 | 140.9.0esr-1~deb12u1 |
| Debian:12 | thunderbird | before 1:140.9.0esr-1~deb12u1 | 1:140.9.0esr-1~deb12u1 |
| Debian:13 | firefox-esr | before 140.9.0esr-1~deb13u1 | 140.9.0esr-1~deb13u1 |
| Debian:13 | thunderbird | before 1:140.9.0esr-1~deb13u1 | 1:140.9.0esr-1~deb13u1 |
| Debian:14 | firefox-esr | before 140.9.0esr-1 | 140.9.0esr-1 |
| Debian:14 | thunderbird | before 1:140.9.0esr-1 | 1:140.9.0esr-1 |
| openSUSE:Leap 15.6 | MozillaThunderbird | before 140.9.0-150200.8.263.1 | 140.9.0-150200.8.263.1 |
| openSUSE:Leap 16.0 | MozillaFirefox | before 140.9.0-160000.1.1 | 140.9.0-160000.1.1 |
| openSUSE:Tumbleweed | firefox-esr | before 140.9.0-1.1 | 140.9.0-1.1 |
| openSUSE:Tumbleweed | MozillaFirefox | before 149.0-1.1 | 149.0-1.1 |
| openSUSE:Tumbleweed | MozillaThunderbird | before 140.9.0-1.1 | 140.9.0-1.1 |
| Red Hat:enterprise_linux_eus:10.0 | firefox | before 0:140.9.0-1.el10_0 | 0:140.9.0-1.el10_0 |
| Red Hat:enterprise_linux_eus:10.0 | firefox-debuginfo | before 0:140.9.0-1.el10_0 | 0:140.9.0-1.el10_0 |
| Red Hat:enterprise_linux_eus:10.0 | firefox-debugsource | before 0:140.9.0-1.el10_0 | 0:140.9.0-1.el10_0 |
| Red Hat:enterprise_linux_eus:10.0 | thunderbird | before 0:140.9.0-1.el10_0 | 0:140.9.0-1.el10_0 |
+84
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
- CVE-2013-1690Mozilla Firefox before 22.0, Firefox ESR 17.x before 17.0.7, Thunderbird before 17.0.7, and Thunderbird ESR 17.x before 17.0.7 do not properKEV86Now
- CVE-2019-17026Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion.KEV79This week
- CVE-2024-9680An attacker was able to achieve code execution in the content process by exploiting a use-after-free in Animation timelines.KEV76This week
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 |
|---|---|---|
| almalinux:firefox | 140.9.0-1.el9_7.alma.1 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:firefox-x11 | 140.9.0-1.el9_7.alma.1 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:thunderbird | 140.9.0-1.el9_7.alma.1 · AlmaLinux:9 | Package registry (OSV) |
| debian:firefox-esr | 140.9.0esr-1~deb12u1 · Debian:12 | Package registry (OSV) |
| debian:thunderbird | 1:140.9.0esr-1~deb12u1 · Debian:12 | Package registry (OSV) |
| opensuse:firefox-esr | 140.9.0-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:MozillaFirefox | 140.9.0-150200.152.225.1 · openSUSE:Leap 15.6 | Package registry (OSV) |
| opensuse:MozillaThunderbird | 140.9.0-150200.8.263.1 · openSUSE:Leap 15.6 | Package registry (OSV) |
| red hat:firefox | 0:140.9.0-1.el9_7 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:firefox-debuginfo | 0:140.9.0-1.el9_7 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:firefox-debugsource | 0:140.9.0-1.el9_7 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:firefox-x11 | 0:140.9.0-1.el9_7 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:thunderbird | 0:140.9.0-1.el9_7 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:thunderbird-debuginfo | 0:140.9.0-1.el9_7 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:thunderbird-debugsource | 0:140.9.0-1.el9_7 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| rocky linux:firefox | 0:140.9.0-1.el9_7 · Rocky Linux:9 | Package registry (OSV) |
| rocky linux:thunderbird | 0:140.9.0-1.el9_7 · Rocky Linux:9 | Package registry (OSV) |
| suse:MozillaFirefox | 140.9.0-150200.152.225.1 · SUSE:Linux Enterprise Module for Desktop Applications 15 SP7 | 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.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
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.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-47020 days apartJIT miscompilation in the JavaScript Engine component39Monitor
- CVE-2026-279628 days apartJIT miscompilation in the JavaScript: WebAssembly component39Monitor
- CVE-2026-16355119 days apartJIT miscompilation in the JavaScript Engine: JIT component39Monitor
- CVE-2026-16410119 days apartJIT miscompilation in the JavaScript Engine: JIT component39Monitor
- CVE-2026-74956147 days apartSame-origin policy bypass in the DOM: Service Workers component36Monitor
- CVE-2026-278328 days apartInformation disclosure due to JIT miscompilation in the JavaScript Engine: JIT component30Monitor
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.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-843 · Access of Resource Using Incompatible Type ('Type Confusion')CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- bugzilla.mozilla.org/show_bug.cgi?id=2020906
- www.mozilla.org/security/advisories/mfsa2026-20/
- www.mozilla.org/security/advisories/mfsa2026-21/
- www.mozilla.org/security/advisories/mfsa2026-22/
- www.mozilla.org/security/advisories/mfsa2026-23/
- www.mozilla.org/security/advisories/mfsa2026-24/
- access.redhat.com/errata/RHSA-2026:5930
- access.redhat.com/errata/RHSA-2026:5931
- access.redhat.com/errata/RHSA-2026:5932
- access.redhat.com/errata/RHSA-2026:6188
- access.redhat.com/errata/RHSA-2026:6342
- access.redhat.com/errata/RHSA-2026:6917
- access.redhat.com/errata/RHSA-2026:7837
- access.redhat.com/errata/RHSA-2026:7838
- access.redhat.com/errata/RHSA-2026:7839
- access.redhat.com/errata/RHSA-2026:7840
- access.redhat.com/errata/RHSA-2026:7841
- access.redhat.com/errata/RHSA-2026:7842
- access.redhat.com/errata/RHSA-2026:7843
- access.redhat.com/errata/RHSA-2026:7845
Vendor advisories and official records. Exploit/PoC links are deliberately left out.