CVE-2023-51437 | Apache Pulsar: Timing attack in SASL token signature verification

Observable timing discrepancy vulnerability in Apache Pulsar SASL Authentication Provider can allow an attacker to forge a SASL Role Token that will pass signature verification. Users are recommended to upgrade to version 2.11.3, 3.0.2, or 3.1.1 which fixes the issue. Users should also consider updating the configured secret in the `saslJaasServerRoleTokenSignerSecretPath` file. Any component matching an above version running the SASL Authentication Provider is affected. That includes the Pulsar Broker, Proxy, Websocket Proxy, or Function Worker. 2.11 Pulsar users should upgrade to at least 2.11.3. 3.0 Pulsar users should upgrade to at least 3.0.2. 3.1 Pulsar users should upgrade to at least 3.1.1. Any users running Pulsar 2.8, 2.9, 2.10, and earlier should upgrade to one of the above patched versions. For additional details on this attack vector, please refer to https://codahale.com/a-lesson-in-timing-attacks/ .

Published: 2024-02-07 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-51437 is rated Moderate Risk (47.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.76%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-51437

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.10% 0.76% +0.67%
2 2025-11-21 0.50% 0.10% -0.40%
3 2025-11-18 — 0.50% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-51437

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.4 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 5.2 [email protected]
7.4 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 5.2 [email protected]

Weakness enumeration for CVE-2023-51437

GitHub Security Advisory for CVE-2023-51437

GHSA-c57v-4vg5-cm2x · Severity: high · Ecosystem: maven — Apache Pulsar SASL Authentication Provider observable timing discrepancy vulnerability

Affected software / configurations for CVE-2023-51437

Vendor Product Version Raw CPE
apache pulsar <= 2.10.5 cpe:2.3:a:apache:pulsar:*:*:*:*:*:*:*:*
apache pulsar >= 2.11.0, < 2.11.3 cpe:2.3:a:apache:pulsar:*:*:*:*:*:*:*:*
apache pulsar >= 3.0.0, < 3.0.2 cpe:2.3:a:apache:pulsar:*:*:*:*:*:*:*:*
apache pulsar 3.1.0 cpe:2.3:a:apache:pulsar:3.1.0:-:*:*:*:*:*:*
apache pulsar 3.1.0 cpe:2.3:a:apache:pulsar:3.1.0:candidate_1:*:*:*:*:*:*

References for CVE-2023-51437

cvelogic Threat Intelligence