CVE-2025-8036Public exploitNetwork attack vector

CORS bypass via stale preflight cache

Published Jul 22, 2025 · Updated Jul 29, 2026

CORS bypass in Mozilla Firefox and Thunderbird before 141, or ESR before 140.1, allows remote attackers to access private services via DNS rebinding. The preflight cache reuses an origin's CORS approval after its hostname resolves to a different IP address, letting script target that new endpoint. The victim must visit an attacker-controlled site; Thunderbird mail reading disables scripting, so exposure requires a browser or browser-like context.

CVSS severity8.1
High
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

CORS bypass in Mozilla Firefox and Thunderbird before 141, or ESR before 140.1, allows remote attackers to access private services via DNS rebinding. The preflight cache reuses an origin's CORS approval after its hostname resolves to a different IP address, letting script target that new endpoint. The victim must visit an attacker-controlled site; Thunderbird mail reading disables scripting, so exposure requires a browser or browser-like context.

The record

CVE
CVE-2025-8036
Published
Jul 22, 2025
Updated
Jul 29, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-350, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 22, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-350Reliance on Reverse DNS Resolution for a Security-Critical Action
T1189Drive-by Compromise

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo