CVE-2026-2764Disclosure(mozilla / firefox)

MEDIUMCVSS 9.8 · CRITICAL

Exploitation observed; activity peaked at 3 mentions and remains active

Immediate actions

Patch mozilla firefox systems immediately
Assume compromise if assets are exposed

Recommended action window: Immediate (within 24h)

NVD description

JIT miscompilation, use-after-free in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

mozilla CVEs Back to dashboard

4.0/ 10 priority

Sources & remediation

Vendor / third-party advisories

Other references

Weakness type (CWE)

CWE-416

Priority

MEDIUM

Exploitation

ACTIVE

PoC

NONE

Patch

AVAILABLE

Momentum

STABLE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

firefox
thunderbird

Threat summary

Active exploitation appears in 2 classified signals
Patch or workaround signal is available
8 mentions across 4 observed days
Momentum state: stable

What's happening

Active exploitation reported across 2 signals
Patch or workaround mentioned in 4 signals
Technical details provided in 5 signals
Disclosure: 4 classified signals
Peaked 3d ago at 3 mentions (2026-02-26); latest day: 1
8 total mentions across 4 days

Affected systems

Vendors

mozilla

Products

firefoxthunderbird

Deep dive

Activity timeline8 mentions / 4d

Signal classification3 categories

Disclosure

450.0%

Active Exploitation

225.0%

Patch

225.0%

Referenced assets4 URLs

By indicator

Classification over time

Date	Total	Labels

2026-02-26	3	Active Exploitation2Patch1
2026-02-28	3	Disclosure3
2026-03-01	1	Disclosure1
2026-04-16	1	Patch1

Full discourse8 posts

Giuseppe Paternicola@giuseppe_1337175d
Patch
🚨 CRITICAL: CVE-2026-2764 (CVSS 9.8) - Use-after-free in Firefox/Thunderbird JIT engine. Network exploitable, no user interaction required. Patch immediately to Firefox 148, ESR 115.33/140.8, Thunderbird 148/140.8. #CVE #PatchNow https://t.co/YcKphDxwUU
Post summary
The tweet alerts about a critical use‑after‑free CVE in Firefox/Thunderbird, urges immediate patching to specified versions, and highlights the high CVSS score.
0000039
25 followersView on X
CRAC Learning - Tech@cracbot221d
Disclosure
CVE-2026-2764 (CVSS:9.8, CRITICAL) is Modified. JIT miscompilation, use-after-free in the JavaScript Engine: JIT component. This vulnerability affects Firefox < 148, Fi..https://nvd.nist.gov/vuln/detail/CVE-2026-2764 #cybersecurityawareness #cybersecurity #CVE #infosec #hacker #nvd #mitre
Post summary
The post announces a critical JIT miscompilation use‑after‑free vulnerability in Firefox’s JavaScript engine (CVSS 9.8), affecting versions below 148.
0000031
173 followersView on X
Infoflowcloud@infoflowcloud222d
Disclosure
🚨*CVE* CVE-2026-2764 JIT miscompilation, use-after-free in the JavaScript Engine: JIT component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8. https://www.cve.org/CVERecord?id=CVE-2026-2764 ----- Traducción: CVE-2026-2764, fallo de… http://infoflow.cloud`
Post summary
The post announces CVE‑2026‑2764, a JIT miscompilation use‑after‑free vulnerability in Firefox’s JavaScript engine, affecting versions below 148 and certain ESR releases.
0000034
55 followersView on X
CVE@CVEnew222d
Disclosure
CVE-2026-2764 JIT miscompilation, use-after-free in the JavaScript Engine: JIT component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8. https://www.cve.org/CVERecord?id=CVE-2026-2764
Post summary
The post announces CVE-2026-2764, a JIT miscompilation and use‑after‑free vulnerability in Firefox’s JavaScript engine, affecting specific Firefox and ESR versions.
00000300
56.6K followersView on X
CRAC Learning - Tech@cracbot222d
Disclosure
CVE-2026-2764 (CVSS:9.8, CRITICAL) is Modified. JIT miscompilation, use-after-free in the JavaScript Engine: JIT component. This vulnerability affects Firefox < 148, Fi..https://nvd.nist.gov/vuln/detail/CVE-2026-2764 #cybersecurityawareness #cybersecurity #CVE #infosec #hacker #nvd #mitre
Post summary
The tweet briefly discloses CVE-2026-2764, noting its critical severity and technical details, but does not provide information on exploitation, patching, or PoC availability.
0000037
173 followersView on X
mysocAi@MysocAi224d
Active Exploitation
[CRITICAL] Critical Vulnerability in Mozilla Firefox and Thunderbird Critical vulnerability in Mozilla Firefox and Thunderbird; update to latest versions. CVE: CVE-2026-2764 • APT: N/A • Status: EXPLOITED IN THE WILD … https://www.thehackerwire.com/vulnerability/CVE-2026-2764/
Post summary
CVE-2026-2764 is a critical vulnerability in Mozilla Firefox and Thunderbird that is actively exploited in the wild; users are advised to update to the latest versions.
000001
3 followersView on X
mysocAi@MysocAi224d
Active Exploitation
[CRITICAL] CVE-2026-2764: Critical Vulnerability in Firefox and Thunderbird Critical vulnerability in Firefox and Thunderbird; patch released. CVE: CVE-2026-2764 • APT: N/A • Status: EXPLOITED Immediate patching requi… https://www.thehackerwire.com/vulnerability/CVE-2026-2764/
Post summary
CVE-2026-2764 is a critical vulnerability affecting Firefox and Thunderbird that is actively exploited in the wild, and a patch has already been released.
000004
3 followersView on X
mysocAi@MysocAi224d
Patch
[CRITICAL] Critical Vulnerability in Mozilla Firefox CVE-2026-2764: Critical vulnerability in Firefox; patch released. CVE: CVE-2026-2764 • APT: N/A • Status: ACTIVE Immediate patching required to prevent exploitation… https://www.thehackerwire.com/vulnerability/CVE-2026-2764/
Post summary
A critical vulnerability (CVE-2026-2764) in Firefox has been disclosed with a patch released; immediate patching is required to prevent potential exploitation.
000002
3 followersView on X

CPE platform detail4 entries

Part:

Vendor:

Product:

Version:

Target SW:

Target HW:

4 of 4 entries

Part	Vendor	Product	Version	Target SW	Target HW
App	mozilla	firefox	-	-	-
App	mozilla	firefox	-	-	-
App	mozilla	thunderbird	-	-	-
App	mozilla	thunderbird	-	-	-

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What researchers are saying

CVE-2026-2764

Giuseppe Paternicola[verified]@giuseppe_1337Patch

The tweet alerts about a critical use‑after‑free CVE in Firefox/Thunderbird, urges immediate patching to specified versions, and highlights the high CVSS score.

mysocAi[verified]@MysocAiActive Exploitation

CVE-2026-2764 is a critical vulnerability in Mozilla Firefox and Thunderbird that is actively exploited in the wild; users are advised to update to the latest versions.

mysocAi[verified]@MysocAiActive Exploitation

CVE-2026-2764 is a critical vulnerability affecting Firefox and Thunderbird that is actively exploited in the wild, and a patch has already been released.

mysocAi[verified]@MysocAiPatch

A critical vulnerability (CVE-2026-2764) in Firefox has been disclosed with a patch released; immediate patching is required to prevent potential exploitation.

CRAC Learning - Tech@cracbotDisclosure

The post announces a critical JIT miscompilation use‑after‑free vulnerability in Firefox’s JavaScript engine (CVSS 9.8), affecting versions below 148.

Infoflowcloud@infoflowcloudDisclosure

The post announces CVE‑2026‑2764, a JIT miscompilation use‑after‑free vulnerability in Firefox’s JavaScript engine, affecting versions below 148 and certain ESR releases.

CVE@CVEnewDisclosure

The post announces CVE-2026-2764, a JIT miscompilation and use‑after‑free vulnerability in Firefox’s JavaScript engine, affecting specific Firefox and ESR versions.

CRAC Learning - Tech@cracbotDisclosure

The tweet briefly discloses CVE-2026-2764, noting its critical severity and technical details, but does not provide information on exploitation, patching, or PoC availability.