FedoraOperating system · Fedoraproject
CVE-2021-29157
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedDovecot before 2.3.15 allows ../ Path Traversal. An attacker with access to the local filesystem can trick OAuth2 authentication into using an HS256 validation key from an attacker-controlled location. This occurs during use of local JWT validation with the posix fs driver.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceDovecot before 2.3.15 contains a path traversal vulnerability (../) in its OAuth2 JWT validation that uses the posix fs driver. An attacker with local filesystem access can exploit this to load an HS256 signing key from an attacker-controlled location by using path traversal sequences, enabling authentication bypass through forged tokens.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
FedoraOperating system
= 33= 34>= 2.3.11, < 2.3.14.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Check installed Dovecot versionRun `doveadm version` or check the package version with `rpm -q dovecot` (Fedora/RHEL) or `dpkg -l dovecot` (Debian). Compare the version number to the affected range (>= 2.3.11 and < 2.3.14.1).Affected if The installed version is 2.3.11, 2.3.12, 2.3.13, 2.3.14, or 2.3.14.1.
-
Verify OAuth2 JWT authentication is enabledInspect the Dovecot configuration files (typically in /etc/dovecot/ or /etc/dovecot/conf.d/). Look for auth mechanisms that enable oauth2 or jwt, such as `auth_mechanisms = ... oauthbearer ...` in dovecot.conf or a related auth configuration file.Affected if OAuth2 or JWT authentication mechanisms are explicitly enabled in the Dovecot configuration.
-
Identify if the posix fs driver is configured for JWTSearch the Dovecot configuration for settings that specify the `posix` driver for token verification. Look for lines containing `token_verif` or `jwtfs` or similar JWT-related settings that point to filesystem-based key storage, such as `jwtfs posix` or a key_path configuration that uses the posix driver.Affected if The configuration specifies the posix fs driver for JWT token verification or key storage.
-
Inspect the configured key file path for JWT validationIf the posix driver is in use, locate the key_path or key_dir setting in the Dovecot configuration. Identify the directory path where HS256 signing keys are stored or referenced.Affected if A key file path is configured for JWT validation and that path is accessible to unprivileged users or allows path traversal.
A user is affected if Dovecot version is between 2.3.11 and 2.3.14.1 inclusive, OAuth2 JWT authentication is enabled, and the posix fs driver is configured for token verification with a key path that could be manipulated via path traversal.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data2.3.14.1
Upgrade Dovecot to version 2.3.15 or later. If upgrade is not immediately feasible, review and restrict filesystem access to the key paths used by the posix fs driver for JWT validation.
Fix this in Fedora
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-29157 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-29157 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data