CVE-2026-2771Disclosure(mozilla / firefox)

LOWCVSS 9.8 · CRITICAL

Signal is active with 1 mentions in latest observed window

Immediate actions

Patch mozilla firefox systems immediately

Recommended action window: Monitor and triage in normal cycle

NVD description

Undefined behavior in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

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0.5/ 10 priority

Sources & remediation

Vendor / third-party advisories

Other references

Weakness type (CWE)

CWE-125

Priority

LOW

Exploitation

NONE

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

Patch or workaround signal is available
5 mentions across 4 observed days
Momentum state: stable

What's happening

Patch or workaround mentioned in 1 signal
Technical details provided in 5 signals
Disclosure: 4 classified signals
Peaked 3d ago at 2 mentions (2026-02-25); latest day: 1
5 total mentions across 4 days

Affected systems

Vendors

mozilla

Products

firefoxthunderbird

Deep dive

Activity timeline5 mentions / 4d

Signal classification2 categories

Disclosure

480.0%

Patch

120.0%

Referenced assets3 URLs

By indicator

Classification over time

Date	Total	Labels

2026-02-25	2	Disclosure2
2026-02-28	1	Disclosure1
2026-03-01	1	Disclosure1
2026-04-16	1	Patch1

Full discourse5 posts

Giuseppe Paternicola@giuseppe_1337175d
Patch
🚨 CRITICAL: CVE-2026-2771 (CVSS 9.8) - Undefined behavior in Firefox/Thunderbird DOM component. Network exploitable, no user interaction required. Patched in Firefox 148, ESR 115.33/140.8, Thunderbird 148/140.8. Update immediately. #CVE #PatchNow https://t.co/0H2V92GICT
Post summary
The tweet alerts users to CVE‑2026‑2771, a critical network‑exploitable flaw in Firefox and Thunderbird, and urges immediate application of the available patches. It provides technical details but no proof of active exploitation or exploit code.
0000032
25 followersView on X
CRAC Learning - Tech@cracbot221d
Disclosure
CVE-2026-2771 (CVSS:9.8, CRITICAL) is Analyzed. Undefined behavior in the DOM: Core & HTML component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Fi..https://nvd.nist.gov/vuln/detail/CVE-2026-2771 #cybersecurityawareness #cybersecurity #CVE #infosec #hacker #nvd #mitre
Post summary
The post announces CVE-2026-2771, a critical DOM-based vulnerability affecting older Firefox versions, with CVSS 9.8, but provides no PoC, exploit, or patch details.
0000026
173 followersView on X
CRAC Learning - Tech@cracbot222d
Disclosure
CVE-2026-2771 (CVSS:9.8, CRITICAL) is Analyzed. Undefined behavior in the DOM: Core & HTML component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Fi..https://nvd.nist.gov/vuln/detail/CVE-2026-2771 #cybersecurityawareness #cybersecurity #CVE #infosec #hacker #nvd #mitre
Post summary
The tweet announces the analysis of CVE‑2026‑2771, detailing an undefined DOM behavior in Firefox with a CVSS of 9.8, but it offers no PoC, patch, or exploitation evidence.
0000047
173 followersView on X
Infoflowcloud@infoflowcloud225d
Disclosure
🚨*CVE* CVE-2026-2771 Undefined behavior in the DOM: Core & HTML component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8. https://www.cve.org/CVERecord?id=CVE-2026-2771 ----- Traducción: CVE-2026-2771 Comportamiento indefinido en el… http://infoflow.cloud`
Post summary
The post announces CVE-2026-2771, describing undefined behavior in Firefox’s DOM core and HTML component that affects versions below 148 and certain ESR releases.
0000045
54 followersView on X
CVE@CVEnew225d
Disclosure
CVE-2026-2771 Undefined behavior in the DOM: Core & HTML component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8. https://www.cve.org/CVERecord?id=CVE-2026-2771
Post summary
The text announces CVE-2026-2771, describing it as undefined behavior in the DOM core and HTML component affecting specific Firefox versions, with no mention of PoC, exploit, or patch.
00000408
56.6K 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-2026-2771

Giuseppe Paternicola[verified]@giuseppe_1337Patch

The tweet alerts users to CVE‑2026‑2771, a critical network‑exploitable flaw in Firefox and Thunderbird, and urges immediate application of the available patches. It provides technical details but no proof of active exploitation or exploit code.

CRAC Learning - Tech@cracbotDisclosure

The post announces CVE-2026-2771, a critical DOM-based vulnerability affecting older Firefox versions, with CVSS 9.8, but provides no PoC, exploit, or patch details.

CRAC Learning - Tech@cracbotDisclosure

The tweet announces the analysis of CVE‑2026‑2771, detailing an undefined DOM behavior in Firefox with a CVSS of 9.8, but it offers no PoC, patch, or exploitation evidence.

Infoflowcloud@infoflowcloudDisclosure

The post announces CVE-2026-2771, describing undefined behavior in Firefox’s DOM core and HTML component that affects versions below 148 and certain ESR releases.

CVE@CVEnewDisclosure

The text announces CVE-2026-2771, describing it as undefined behavior in the DOM core and HTML component affecting specific Firefox versions, with no mention of PoC, exploit, or patch.