Firefox ESR: Improperly Controlled Modification of Object Prototype Attributes
CVE-2022-1802 is a high-severity improperly controlled modification of object prototype attributes vulnerability in Firefox ESR from Mozilla, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 91.9.1 as the first without the flaw, so updating Firefox ESR to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 28.5% chance of exploitation within 30 days, which is in the top 1.84% of all scored CVEs.
EPSS places it among the vulnerabilities most likely to be exploited soon.
What to do
- Update Firefox ESR to 91.9.1 or a later version.
- Update Firefox to 100.0.2 or a later version.
- Update Firefox for Android to 100.3.0 or a later version.
- Read the advisory on bugzilla.mozilla.org for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Mozilla | Firefox ESR | before 91.9.1 | 91.9.1 |
| Mozilla | Firefox | before 100.0.2 | 100.0.2 |
| Mozilla | Firefox for Android | before 100.3.0 | 100.3.0 |
| Mozilla | Thunderbird | before 91.9.1 | 91.9.1 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | NVD |
| CVSS 3.1 | 8.8 | High | CISA (ADP) |
Official description
If an attacker was able to corrupt the methods of an Array object in JavaScript via prototype pollution, they could have achieved execution of attacker-controlled JavaScript code in a privileged context. This vulnerability affects Firefox ESR < 91.9.1, Firefox < 100.0.2, Firefox for Android < 100.3.0, and Thunderbird < 91.9.1.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improperly Controlled Modification of Object Prototype Attributes
The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.
How developers prevent this class of flaw
- By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
- By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
- When handling untrusted objects, validating using a schema can be used.
More Improperly Controlled Modification of Object Prototype Attributes vulnerabilities (CWE-1321)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- bugzilla.mozilla.org/show_bug.cgi?id=1770137Issue Tracking, Permissions Required
- mozilla.org/security/advisories/mfsa2022-19/
Other vulnerabilities in Firefox ESR
- 9.8 Critical severity
- 8.8 High severity
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- 7.5 High severity
Recent Improperly Controlled Modification of Object Prototype Attributes vulnerabilities
- 8.8 High severity
- 8.8 High severity
- 9.8 Critical severity
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
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