Thunderbird: Incorrect Default Permissions
CVE-2022-29909 is a high-severity incorrect default permissions vulnerability in Thunderbird 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 as the first without the flaw, so updating Thunderbird to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.89% chance of exploitation within 30 days, higher than 60% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Thunderbird to 91.9 or a later version.
- Update Firefox ESR to 91.9 or a later version.
- Update Firefox to 100 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 | Thunderbird | before 91.9 | 91.9 |
| Mozilla | Firefox ESR | before 91.9 | 91.9 |
| Mozilla | Firefox | before 100 | 100 |
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
Documents in deeply-nested cross-origin browsing contexts could have obtained permissions granted to the top-level origin, bypassing the existing prompt and wrongfully inheriting the top-level permissions. This vulnerability affects Thunderbird < 91.9, Firefox ESR < 91.9, and Firefox < 100.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incorrect Default Permissions
During installation, installed file permissions are set to allow anyone to modify those files.
How developers prevent this class of flaw
- The architecture needs to access and modification attributes for files to only those users who actually require those actions.
- Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
More Incorrect Default Permissions vulnerabilities (CWE-276)
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=1755081Issue Tracking, Permissions Required
- mozilla.org/security/advisories/mfsa2022-16/
- mozilla.org/security/advisories/mfsa2022-17/
- mozilla.org/security/advisories/mfsa2022-18/Mailing List
Other vulnerabilities in Thunderbird
- 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 Incorrect Default Permissions vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 8.4 High severity
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