CVE-2024-27094 | OpenZeppelin Contracts base64 encoding may read from potentially dirty memory

OpenZeppelin Contracts is a library for secure smart contract development. The `Base64.encode` function encodes a `bytes` input by iterating over it in chunks of 3 bytes. When this input is not a multiple of 3, the last iteration may read parts of the memory that are beyond the input buffer. The vulnerability is fixed in 5.0.2 and 4.9.6.

Published: 2024-03-21 Last update: 2025-12-04 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2024-27094 is rated Moderate Risk (50/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.56%). 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-2024-27094

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 2025-12-05 0.18% 0.56% +0.39%
2 2025-11-21 0.45% 0.18% -0.27%
3 2025-11-18 — 0.45% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2024-27094

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H 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:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 4.2 [email protected]
7.4 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H 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:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 5.2 [email protected]

Weakness enumeration for CVE-2024-27094

GitHub Security Advisory for CVE-2024-27094

GHSA-9vx6-7xxf-x967 · Severity: medium · Ecosystem: npm — OpenZeppelin Contracts base64 encoding may read from potentially dirty memory

Affected software / configurations for CVE-2024-27094

Vendor Product Version Raw CPE
openzeppelin contracts >= 4.5.0, < 4.9.6 cpe:2.3:a:openzeppelin:contracts:*:*:*:*:*:node.js:*:*
openzeppelin contracts >= 5.0.0, < 5.0.2 cpe:2.3:a:openzeppelin:contracts:*:*:*:*:*:node.js:*:*
openzeppelin contracts_upgradeable >= 4.5.0, <= 4.9.6 cpe:2.3:a:openzeppelin:contracts_upgradeable:*:*:*:*:*:node.js:*:*
openzeppelin contracts_upgradeable >= 5.0.0, < 5.0.2 cpe:2.3:a:openzeppelin:contracts_upgradeable:*:*:*:*:*:node.js:*:*

References for CVE-2024-27094

cvelogic Threat Intelligence