CVE-2026-2763Disclosure(mozilla / firefox)

MEDIUMCVSS 9.8 · CRITICAL

Exploit discussion active in current signal (1 latest mentions)

Immediate actions

Patch mozilla firefox systems immediately
Hunt for exploitation attempts and persistence artifacts
Increase monitoring for publicly documented tradecraft

Recommended action window: High priority (within 72h)

NVD description

Use-after-free in the JavaScript Engine 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

NONE

PoC

YES

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

Public PoC and exploit tooling are both present
Patch or workaround signal is available
6 mentions across 4 observed days
Momentum state: stable

What's happening

Exploit tool or code specified in 1 signal
PoC mentioned or linked in 1 signal
Patch or workaround mentioned in 2 signals
Technical details provided in 5 signals
Disclosure: 4 classified signals
Peaked 3d ago at 3 mentions (2026-02-28); latest day: 1
6 total mentions across 4 days

Affected systems

Vendors

mozilla

Products

firefoxthunderbird

Deep dive

Activity timeline6 mentions / 4d

Signal classification3 categories

Disclosure

466.7%

PoC

116.7%

Patch

116.7%

Referenced assets4 URLs

By indicator

Classification over time

Date	Total	Labels

2026-02-28	3	Disclosure3
2026-03-01	1	Disclosure1
2026-03-06	1	PoC1
2026-04-16	1	Patch1

Full discourse6 posts

Giuseppe Paternicola@giuseppe_1337176d
Patch
🚨 CRITICAL: CVE-2026-2763 (CVSS 9.8) - Use-after-free in Firefox/Thunderbird JavaScript Engine. Network exploitable, no user interaction required. Patch NOW: Firefox 148, ESR 115.33/140.8, Thunderbird 148/140.8. #CVE #PatchNow #ThreatIntel https://t.co/E1laCJJBoX
Post summary
The Tweet announces a critical use‑after‑free flaw in Firefox/Thunderbird, stresses immediate patching, but does not reference a PoC or active exploitation evidence.
0000046
25 followersView on X
pon able@BINARYIDA216d
PoC
Since the bug is already patched and the opportunity for Pwn2Own is gone, I’ve decided to release my Writeup & PoC. https://github.com/ppwwiinn/CVE-2026-2763-POC/
Post summary
The author releases a writeup and PoC for CVE‑2026‑2763, noting the vulnerability has already been patched and no active exploitation is reported.
00000207
View on X
CRAC Learning - Tech@cracbot221d
Disclosure
CVE-2026-2763 (CVSS:9.8, CRITICAL) is Modified. Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firef..https://nvd.nist.gov/vuln/detail/CVE-2026-2763 #cybersecurityawareness #cybersecurity #CVE #infosec #hacker #nvd #mitre
Post summary
The post announces CVE-2026-2763, a critical use‑after‑free vulnerability in Firefox’s JavaScript engine, providing technical details but no PoC, exploit, or patch information.
0000027
173 followersView on X
Infoflowcloud@infoflowcloud222d
Disclosure
🚨*CVE* CVE-2026-2763 Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8. https://www.cve.org/CVERecord?id=CVE-2026-2763 ----- Traducción: CVE-2026-2763 Uso de memoria previamente liberad… http://infoflow.cloud`
Post summary
The post announces CVE‑2026‑2763, a use‑after‑free bug in Firefox’s JavaScript engine affecting versions below 148 and certain ESR releases.
0000042
55 followersView on X
CVE@CVEnew222d
Disclosure
CVE-2026-2763 Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8. https://www.cve.org/CVERecord?id=CVE-2026-2763
Post summary
A use‑after‑free vulnerability (CVE‑2026‑2763) in Firefox’s JavaScript engine is disclosed, affecting specific Firefox and ESR versions.
00000359
56.6K followersView on X
CRAC Learning - Tech@cracbot222d
Disclosure
CVE-2026-2763 (CVSS:9.8, CRITICAL) is Modified. Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firef..https://nvd.nist.gov/vuln/detail/CVE-2026-2763 #cybersecurityawareness #cybersecurity #CVE #infosec #hacker #nvd #mitre
Post summary
The post announces CVE‑2026‑2763, lists its severity and affected versions, but contains no PoC, exploit code, active exploitation claims, or patch information.
0000035
173 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	-	-	-

Explore more

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What researchers are saying

CVE-2026-2763

Giuseppe Paternicola[verified]@giuseppe_1337Patch

The Tweet announces a critical use‑after‑free flaw in Firefox/Thunderbird, stresses immediate patching, but does not reference a PoC or active exploitation evidence.

pon able@BINARYIDAPoC

The author releases a writeup and PoC for CVE‑2026‑2763, noting the vulnerability has already been patched and no active exploitation is reported.

CRAC Learning - Tech@cracbotDisclosure

The post announces CVE-2026-2763, a critical use‑after‑free vulnerability in Firefox’s JavaScript engine, providing technical details but no PoC, exploit, or patch information.

Infoflowcloud@infoflowcloudDisclosure

The post announces CVE‑2026‑2763, a use‑after‑free bug in Firefox’s JavaScript engine affecting versions below 148 and certain ESR releases.

CVE@CVEnewDisclosure

A use‑after‑free vulnerability (CVE‑2026‑2763) in Firefox’s JavaScript engine is disclosed, affecting specific Firefox and ESR versions.

CRAC Learning - Tech@cracbotDisclosure

The post announces CVE‑2026‑2763, lists its severity and affected versions, but contains no PoC, exploit code, active exploitation claims, or patch information.