CVE-2025-8027: mozilla firefox Use of Uninitialized Variable
CVSS: 6.5v3.1MediumModified
AliasesUBUNTU-CVE-2025-8027DEBIAN-CVE-2025-8027CGA-453r-w8q9-2jwpCGA-hx3f-9mr7-j3wpCGA-h57v-6qcg-x2gwCGA-m5wj-5hv7-pqc2
Published 22-07-2025Last modified 13-04-2026
Vulnerability summary
CVE-2025-8027 is a medium (CVSS 6.5) Use of Uninitialized Variable vulnerability in mozilla firefox. EPSS estimates a 0.40% chance of exploitation in the next 30 days, higher than 32.9% of scored vulnerabilities.
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)EPSS score
0.40%
0%100%
Low · +0.04 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 37 · Related 12DLA-4250-1DLA-4253-1DSA-5964-1DSA-5966-1MGASA-2025-0227MGASA-2025-0228OPENSUSE-SU-2025-20135-1OPENSUSE-SU-2025:15371-1OPENSUSE-SU-2025:15383-1OPENSUSE-SU-2025:15386-1OPENSUSE-SU-2025:15387-1OPENSUSE-SU-2025:20135-1RHSA-2025:11747RHSA-2025:11748RHSA-2025:11797RHSA-2025:12044RHSA-2025:12045RHSA-2025:12046RHSA-2025:12187RHSA-2025:12188RHSA-2025:12278RHSA-2025:12302RHSA-2025:12353RHSA-2025:12360RHSA-2025:12361RHSA-2025:13645RHSA-2025:13646RHSA-2025:13647RHSA-2025:13648RHSA-2025:13649RHSA-2025:13650RHSA-2025:13651RHSA-2025:13676SUSE-SU-2025:02529-1SUSE-SU-2025:02531-1SUSE-SU-2025:02546-1SUSE-SU-2025:21170-1CGA-RRM4-PHJG-9C3XUSN-7991-1
Timeline
- 22-07-2025PublishedVulnerability first disclosed.
- 13-04-2026Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
6 scores · 6 sources · 1 versionMedium 6.5Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:NSourcesAll 6 agree
- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
- OSV · WolfiEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
- OSV · ChainguardEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
- NVDNIST6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
EPSS trend
Probability
0.40%
Chance of exploitation in the next 30 days
Percentile
33%
Versus all other CVEs
30-day change
+0.04 pp
From 0.36% on 19-09-2026
19-09-202619-10-2026
EPSS score0.40%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu8 products
- mozjs102All versions (No fix recorded)
- mozjs115All versions (No fix recorded)
- mozjs38All versions (No fix recorded)
- mozjs52All versions (No fix recorded)
- mozjs68All versions (No fix recorded)
Chainguard2 products
- firefox< 128.13-r0
- firefox-esr< 140.1-r0
Debian2 products
- firefox-esr< 128.13.0esr-1~deb12u1 | < 128.13.0esr-1
- thunderbird< 1:128.13.0esr-1~deb12u1 | < 1:128.13.0esr-1
Mozilla2 products
- firefox< 115.26.0 | < 141.0 | ≥ 128.0, < 128.13.0 | ≥ 140.0, < 140.1.0
- thunderbird< 128.13.0 | < 141.0 | ≥ 140.0, < 140.1.0
Wolfi1 product
- firefox< 128.13-r0
5 vendors · 15 products
