EUVD-2026-42213
GHSA-j5fh-pqqw-m384
Severity by source
AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Network-reachable LDAP bind endpoint (AV:N), high complexity due to PBKDF2 timing noise (AC:H), no authentication needed to bind (PR:N), low confidentiality-only impact limited to partial hash inference.
Primary rating from Vendor (redhat).
CVSS VectorVendor: redhat
Lifecycle Timeline
2DescriptionCVE.org
A flaw was found in 389 Directory Server. The PBKDF2-SHA256 password verification function uses standard memcmp() for comparing password hashes instead of a constant-time comparison function. A remote attacker could potentially use timing measurements of LDAP bind attempts to infer partial hash information, though practical exploitation is extremely difficult due to PBKDF2 computational overhead.
AnalysisAI
Timing side-channel exposure in Red Hat Directory Server's PBKDF2-SHA256 password verification allows a remote unauthenticated attacker to send repeated LDAP bind requests and statistically infer partial hash information by measuring response-time differences caused by non-constant-time memcmp() comparisons. Affected deployments span Red Hat Directory Server 11 through 13 and the 389-ds-base package shipped across RHEL 6 through 10. No public exploit identified at time of analysis, and practical exploitation is acknowledged to be extremely difficult due to the computational overhead inherent in PBKDF2 key stretching, which substantially degrades the timing signal.
Technical ContextAI
389 Directory Server implements PBKDF2-SHA256 for hashing LDAP user passwords, a key-derivation function that applies a pseudo-random function thousands of times to increase brute-force cost. The root cause (CWE-208, Observable Timing Discrepancy) is that the final hash comparison step uses the standard C library memcmp(), which returns early on the first byte mismatch. This produces microsecond-scale timing differences depending on how many leading bytes of the submitted hash match the stored hash. PBKDF2's deliberate computational overhead (intended as a brute-force deterrent) partially masks the memcmp timing signal, which is why practical exploitation is rated extremely difficult. Affected CPE strings confirm all major RHDS versions (cpe:2.3:a:red_hat:red_hat_directory_server_11/12/13) and the 389-ds-base component across RHEL 6-10.
RemediationAI
No specific patched version number is identified in the available intelligence; an exact fix release has not been independently confirmed from the provided references. Administrators should consult the Red Hat security advisory at https://access.redhat.com/security/cve/CVE-2026-15041 and monitor errata for 389-ds-base updates that replace memcmp() with a constant-time comparison (e.g., CRYPTO_memcmp or timingsafe_bcmp). As a compensating control while awaiting a patch, restrict LDAP bind access to trusted network segments via firewall rules - this limits an attacker's ability to issue the high volume of bind attempts required for statistical timing analysis. Additionally, enabling account lockout policies in Directory Server (via passwordLockout and passwordMaxFailure attributes) reduces the number of probes an attacker can make before triggering a lockout, further degrading timing-attack feasibility. Note that lockout policies introduce a denial-of-service trade-off against legitimate users.
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External POC / Exploit Code
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