Mozilla Firefox Use-After-Free
CVE-2022-26486 is a critical-severity use after free vulnerability in Firefox from Mozilla, with a CVSS 3.1 base score of 9.6 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 97.0.2 as the first without the flaw, so updating Firefox to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on March 7, 2022, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Firefox to 97.0.2 or a later version.
- Update Firefox ESR to 91.6.1 or a later version.
- Update Firefox for Android to 97.3.0 or a later version.
- CISA's required action: Apply updates per vendor instructions.
- 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 | before 97.0.2 | 97.0.2 |
| Mozilla | Firefox ESR | before 91.6.1 | 91.6.1 |
| Mozilla | Firefox for Android | before 97.3.0 | 97.3.0 |
| Mozilla | Thunderbird | before 91.6.2 | 91.6.2 |
| Mozilla | Focus | before 97.3.0 | 97.3.0 |
| Mozilla | Firefox Focus | before 97.3.0 | 97.3.0 |
| Mozilla | Firefox Mobile | before 97.3.0 | 97.3.0 |
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
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- 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:C/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.6 | Critical | NVD |
| CVSS 3.1 | 9.6 | Critical | CISA (ADP) |
Official description
An unexpected message in the WebGPU IPC framework could lead to a use-after-free and exploitable sandbox escape. We have had reports of attacks in the wild abusing this flaw. This vulnerability affects Firefox < 97.0.2, Firefox ESR < 91.6.1, Firefox for Android < 97.3.0, Thunderbird < 91.6.2, and Focus < 97.3.0.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CVE record published.
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- bugzilla.mozilla.org/show_bug.cgi?id=1758070Exploit, Issue Tracking
- mozilla.org/security/advisories/mfsa2022-09/Exploit
Third-party and government advisories
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2022-26486US Government Resource
Other vulnerabilities in Firefox
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
Recent Use After Free vulnerabilities
- 9.8 Critical severity
- 8.8 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.5 High severity
- 8.8 High severity
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