CVE-2026-8973 | Memory safety bugs fixed in Firefox 151

Memory safety bugs present in Firefox 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 151 and Thunderbird 151.

Published: 2026-05-19 Last update: 2026-05-26 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-8973 is rated Low Risk (39.5/100): CVSS High severity, with low exploitation likelihood (EPSS 0.04%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

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-2026-8973

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 2026-05-20 — 0.04% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-8973

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.8 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
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.
 2.8 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-8973

GitHub Security Advisory for CVE-2026-8973

GHSA-f4hm-8h94-gvp6 · Severity: critical — Memory safety bugs present in Firefox 150. Some of these bugs showed evidence of memory...

OS Trackers for CVE-2026-8973

vendor priority summary link
debian not yet assigned CVE-2026-8973 not yet assigned priority: Debian including 1 source packages (firefox), 1 status rows across 1 suites (sid): resolved 1. https://security-tracker.debian.org/tracker/CVE-2026-8973
suse high — https://www.suse.com/security/cve/CVE-2026-8973/
ubuntu medium CVE-2026-8973 medium priority: Ubuntu including 9 source packages (firefox, mozjs102, …), 49 status rows across 7 suites (bionic, focal, jammy, noble, questing, resolute, upstream): DNE 23, needs-triage 10, ignored 8, not-affected 7, needed 1. https://ubuntu.com/security/CVE-2026-8973

Affected software / configurations for CVE-2026-8973

Vendor Product Version Raw CPE
mozilla firefox < 151.0.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
mozilla thunderbird < 151.0.0 cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*

References for CVE-2026-8973

URL Tags
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1362365%2C1860538%2C1929005%2C1983353%2C1998526%2C2023271%2C2023943%2C2024244%2C2024260%2C2024443%2C2024665%2C2024774%2C2024916%2C2025346%2C2025357%2C2025406%2C2025434%2C2025488%2C2025496%2C2025942%2C2025947%2C2025968%2C2026279%2C2027159%2C2027239%2C2027276%2C2027308%2C2027310%2C2027324%2C2027329%2C2027363%2C2027381%2C2027382%2C2027383%2C2028274%2C2028884%2C2029060%2C2029065%2C2029068%2C2029281%2C2029293%2C2029297%2C2029303%2C2029439%2C2029448%2C2029703%2C2029720%2C2029721%2C2029723%2C2029770%2C2029771%2C2029782%2C2029818%2C2029885%2C2030100%2C2030379%2C2030385%2C2030979%2C2031119%2C2031122%2C2034119%2C2034791%2C2035209%2C2036666%2C2037986 Broken Link
https://www.mozilla.org/security/advisories/mfsa2026-46/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-50/ Vendor Advisory
cvelogic Threat Intelligence