CVE-2024-9394: Mozilla Firefox · Cross-origin access to JSON contents through multipart responses
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 6.1 Medium · fixed in 131 : update Mozilla Firefox when convenient.
Data as of 25 Oct 2026, 19:02 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 131, 128.3, 115.16
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 1 Oct 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.
What to do
Upgrade Mozilla Firefox to 131, 128.3 or 115.16.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mozilla Firefox | Affected
| Fixed in
|
AI-suggested
If you cannot patch yet, organizations should implement network-level controls to block or inspect suspicious multipart HTTP responses, especially from untrusted or external sources. Security teams should educate users about the risks of interacting with untrusted links or sites that could deliver malicious multipart responses. Deploying endpoint protection solutions capable of detecting anomalous browser behaviors related to script execution under privileged origins can provide additional defense. On Android devices, enforcing strict app update policies and restricting installation of untrusted applications can reduce exposure. Monitoring browser telemetry and logs for unusual resource://devtools activity may help detect exploitation attempts. Finally, organizations should review and enhance their web content security policies and consider disabling or restricting features that allow resource://devtools origin script execution if feasible.
Description
An attacker could, via a specially crafted multipart response, execute arbitrary JavaScript under the `resource://devtools` origin. This could allow them to access cross-origin JSON content. This access is limited to "same site" documents by the Site Isolation feature on desktop clients, but full cross-origin access is possible on Android versions. This vulnerability affects Firefox < 131, Firefox ESR < 128.3, Firefox ESR < 115.16, Thunderbird < 128.3, and Thunderbird < 131.
References
- bugzilla.mozilla.org/show_bug.cgi?id=1918874 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2024-46/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2024-47/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2024-48/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2024-49/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2024-50/ (opens in a new tab)
- lists.debian.org/debian-lts-announce/2024/10/msg00006.html (opens in a new tab)
- lists.debian.org/debian-lts-announce/2024/10/msg00004.html (opens in a new tab)