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CVE-2025-8027· NVD / CVE Program· CNA mozilla

JavaScript engine only wrote partial return value to stack

On 64-bit platforms IonMonkey-JIT only wrote 32 bits of the 64-bit return value space on the stack. Baseline-JIT, however, read the entire 64 bits. This vulnerability was fixed in Firefox 141, Firefox ESR 115.26, Firefox ESR 128.13, Firefox ESR 140.1, Thunderbird 141, Thunderbird 128.13, and Thunderbird 140.1.

MediumCVSS 6.5 · v3.1—No exploit Fix available

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Published
Jul 22, 2025
Updated
Sep 30, 2026
EPSS
0.4% · 29th percentile
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Report tools

JSON

Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Affected systems

VendorProduct
mozillafirefox
mozillathunderbird

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • mozilla firefoxbefore 115.26.0
  • mozilla firefoxbefore 141.0
  • mozilla firefox128.0 and later · before 128.13.0
  • mozilla firefox140.0 and later · before 140.1.0
  • mozilla thunderbirdbefore 128.13.0
  • mozilla thunderbirdbefore 141.0
  • mozilla thunderbird140.0 and later · before 140.1.0

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

    • 115.26 and later · up to and including 115.*not affected · rpm
    • 128.13 and later · up to and including 128.*not affected · rpm
    • 140.1 and later · up to and including 140.*not affected · rpm
    • 141 and laternot affected · rpm
  • Mozilla Thunderbird

    • 128.13 and later · up to and including 128.*not affected · rpm
    • 140.1 and later · up to and including 140.*not affected · rpm
    • 141 and laternot affected · rpm

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10firefoxbefore 128.13.0-1.el10_0128.13.0-1.el10_0
AlmaLinux:10thunderbirdbefore 128.13.0-3.el10_0.alma.1128.13.0-3.el10_0.alma.1
AlmaLinux:8firefoxbefore 128.13.0-1.el8_10.alma.1128.13.0-1.el8_10.alma.1
AlmaLinux:8thunderbirdbefore 128.13.0-3.el8_10.alma.1128.13.0-3.el8_10.alma.1
AlmaLinux:9firefoxbefore 128.13.0-1.el9_6.alma.1128.13.0-1.el9_6.alma.1
AlmaLinux:9firefox-x11before 128.13.0-1.el9_6.alma.1128.13.0-1.el9_6.alma.1
AlmaLinux:9thunderbirdbefore 128.13.0-3.el9_6.alma.1128.13.0-3.el9_6.alma.1
Debian:11firefox-esrbefore 128.13.0esr-1~deb11u1128.13.0esr-1~deb11u1
Debian:11thunderbirdbefore 1:128.13.0esr-1~deb11u11:128.13.0esr-1~deb11u1
Debian:12firefox-esrbefore 128.13.0esr-1~deb12u1128.13.0esr-1~deb12u1
Debian:12thunderbirdbefore 1:128.13.0esr-1~deb12u11:128.13.0esr-1~deb12u1
Debian:13firefox-esrbefore 128.13.0esr-1128.13.0esr-1
Debian:13thunderbirdbefore 1:128.13.0esr-11:128.13.0esr-1
openSUSE:Leap 16.0mozjs128before 128.14.0-160000.1.1128.14.0-160000.1.1
openSUSE:Tumbleweedfirefox-esrbefore 140.1.0-1.1140.1.0-1.1
openSUSE:TumbleweedMozillaFirefoxbefore 141.0-1.1141.0-1.1
openSUSE:TumbleweedMozillaThunderbirdbefore 140.1.0-1.1140.1.0-1.1
openSUSE:Tumbleweedmozjs128before 128.13.0-1.1128.13.0-1.1
Red Hat:enterprise_linux:10.0firefoxbefore 0:128.13.0-1.el10_00:128.13.0-1.el10_0
Red Hat:enterprise_linux:10.0firefox-debuginfobefore 0:128.13.0-1.el10_00:128.13.0-1.el10_0
Red Hat:enterprise_linux:10.0firefox-debugsourcebefore 0:128.13.0-1.el10_00:128.13.0-1.el10_0
Red Hat:enterprise_linux:10.0thunderbirdbefore 0:128.13.0-3.el10_00:128.13.0-3.el10_0
Red Hat:enterprise_linux:10.0thunderbird-debuginfobefore 0:128.13.0-3.el10_00:128.13.0-3.el10_0
Red Hat:enterprise_linux:10.0thunderbird-debugsourcebefore 0:128.13.0-3.el10_00:128.13.0-3.el10_0

+87

Other 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 befKEV
    94Now
  • CVE-2019-11708Insufficient vetting of parameters passed with the Prompt:Open IPC message between child and parent processes can result in the non-sandboxeKEV
    87Now
  • 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 bypassKEV
    86Now
  • 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 properKEV
    86Now
  • CVE-2019-17026Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion.KEV
    79This week
  • CVE-2024-9680An attacker was able to achieve code execution in the content process by exploiting a use-after-free in Animation timelines.KEV
    76This 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 / packageFixed versionSource
almalinux:firefox128.13.0-1.el8_10.alma.1 · AlmaLinux:8Package registry (OSV)
almalinux:firefox-x11128.13.0-1.el9_6.alma.1 · AlmaLinux:9Package registry (OSV)
almalinux:thunderbird128.13.0-3.el9_6.alma.1 · AlmaLinux:9Package registry (OSV)
debian:firefox-esr128.13.0esr-1~deb12u1 · Debian:12Package registry (OSV)
debian:thunderbird1:128.13.0esr-1~deb12u1 · Debian:12Package registry (OSV)
opensuse:firefox-esr140.1.0-1.1 · openSUSE:TumbleweedPackage registry (OSV)
opensuse:MozillaFirefox140.1.0-150200.152.193.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:MozillaFirefox-branding-SLE140-150200.9.21.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:MozillaThunderbird140.1.0-150200.8.230.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:mozjs128128.14.0-160000.1.1 · openSUSE:Leap 16.0Package registry (OSV)
red hat:firefox0:128.13.0-1.el8_10 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:firefox-debuginfo0:128.13.0-1.el8_10 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:firefox-debugsource0:128.13.0-1.el8_10 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:firefox-x110:128.13.0-1.el9_6 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:thunderbird0:128.13.0-3.el9_6 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:thunderbird-debuginfo0:128.13.0-3.el9_6 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:thunderbird-debugsource0:128.13.0-3.el9_6 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
rocky linux:firefox0:128.13.0-1.el8_10 · Rocky Linux:8Package registry (OSV)
rocky linux:thunderbird0:128.13.0-3.el9_6 · Rocky Linux:9Package registry (OSV)
suse:MozillaFirefox140.1.0-150200.152.193.1 · SUSE:Linux Enterprise Module for Desktop Applications 15 SP6Package registry (OSV)
suse:MozillaFirefox-branding-SLE140-150200.9.21.1 · SUSE:Linux Enterprise Module for Desktop Applications 15 SP6Package registry (OSV)
suse:MozillaThunderbird140.1.0-150200.8.230.1 · SUSE:Linux Enterprise Module for Package Hub 15 SP6Package registry (OSV)
suse:mozjs128128.14.0-160000.1.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)
suse:pipewire0.3.6-150200.3.11.1 · SUSE:Linux Enterprise Module for Package Hub 15 SP6Package registry (OSV)
suse:xdg-desktop-portal1.8.0-150200.5.8.1 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSPackage 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.

EPSS, last 120 days

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.

Finders, 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-2026-6748273 days apartUninitialized memory in the Audio/Video: Web Codecs component
    39Monitor
  • CVE-2026-92052420 days apartPrivilege escalation due to uninitialized memory in the Graphics: CanvasWebGL component
    35Monitor
  • CVE-2026-6751273 days apartUninitialized memory in the Audio/Video: Web Codecs component
    29Monitor
  • CVE-2025-918128 days apartUninitialized memory in the JavaScript Engine component
    26Monitor
  • CVE-2026-100799434 days apartUninitialized memory in the Graphics: WebGPU component
    17Monitor
  • CVE-2026-100802434 days apartUninitialized memory in the Graphics: WebGPU component
    17Monitor

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

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

nvd-secondary

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.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

All records