CVE-2025-5269 | Memory safety bug fixed in Firefox ESR 128.11 and Thunderbird 128.11

Memory safety bug present in Firefox ESR 128.10, and Thunderbird 128.10. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox ESR 128.11 and Thunderbird 128.11.

Published: 2025-05-27 Last update: 2026-04-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-5269 is rated Moderate Risk (54.5/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.43%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-5269

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-23 0.06% 0.43% +0.37%
2 2025-11-04 0.04% 0.06% +0.02%
3 2025-10-23 — 0.04% —

Full EPSS history (7 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-5269

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.1 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2025-5269

OS Trackers for CVE-2025-5269

vendor priority summary link
alpine — CVE-2025-5269: 3 source package rows (firefox, firefox-esr, thunderbird); 293 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 293. https://security.alpinelinux.org/vuln/CVE-2025-5269
debian not yet assigned CVE-2025-5269 not yet assigned priority: Debian including 2 source packages (firefox-esr, thunderbird), 10 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 10. https://security-tracker.debian.org/tracker/CVE-2025-5269
redhat medium — https://access.redhat.com/security/cve/CVE-2025-5269
suse high CVE-2025-5269 severity important: SUSE including 36 source package names (2.1.3-4.11:qemu-guest-agent-8.2.7-1.1, MozillaFirefox-128.11.0-112.262.1, …), 145 product×package rows across 50 product lines (Container suse/kiosk/firefox-esr, Container suse/sl-micro/6.0/kvm-os-container, … (50 product lines)): Fixed 142, First Fixed 3. https://www.suse.com/security/cve/CVE-2025-5269/
ubuntu medium CVE-2025-5269 medium priority: Ubuntu including 1 source packages (thunderbird), 6 status rows across 6 suites (focal, jammy, noble, oracular, plucky, upstream): not-affected 3, released 2, DNE 1. https://ubuntu.com/security/CVE-2025-5269

Affected software / configurations for CVE-2025-5269

Vendor Product Version Raw CPE
mozilla firefox < 128.11.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
mozilla thunderbird < 128.11.0 cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

References for CVE-2025-5269

cvelogic Threat Intelligence