CVE-2021-29157Public exploit

Account impersonation via unescaped JWT key identifiers

Published Jun 28, 2021 · Updated Aug 3, 2024

Path traversal in Dovecot IMAP Server 2.3.11 through 2.3.14 allows local users to authenticate as any valid user with forged JWTs. OAuth2 local JWT validation with the posix fs driver fails to escape attacker-controlled kid and azp fields before using them to select an HS256 key file. Exploitation requires write access to a Dovecot-readable local path; the substituted key validates forged tokens that expose another user's email.

CVSS severity6.7
Medium
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Dovecot IMAP Server 2.3.11 through 2.3.14 allows local users to authenticate as any valid user with forged JWTs. OAuth2 local JWT validation with the posix fs driver fails to escape attacker-controlled kid and azp fields before using them to select an HS256 key file. Exploitation requires write access to a Dovecot-readable local path; the substituted key validates forged tokens that expose another user's email.

The record

CVE
CVE-2021-29157
Published
Jun 28, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-22, CWE-24, T1606
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

2.1NVDAV:L/AC:L/Au:N/C:P/I:N/A:N
6.7OX Software GmbHCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
7.5MITRECVSS:3.1/AC:H/AV:L/A:N/C:H/I:H/PR:L/S:C/UI:N
5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-24Path Traversal: '../filedir'
T1606Forge Web Credentials

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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