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OpenSSLFramework / library

CVE-2021-23840

HIGH · 7.5 CVSS v3.1 Published 2021-02-16
Fix available
A fix is available. Upgrade to 1.0.2y / 1.1.1j or later.
See remediation →
84/100
Remediation priority · High
High EPSS Remotely reachable No privileges Zero-click Patch available

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 · unedited
Calls to EVP_CipherUpdate, EVP_EncryptUpdate and EVP_DecryptUpdate may overflow the output length argument in some cases where the input length is close to the maximum permissable length for an integer on the platform. In such cases the return value from the function call will be 1 (indicating success), but the output length value will be negative. This could cause applications to behave incorrectly or crash. OpenSSL versions 1.1.1i and below are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1j. OpenSSL versions 1.0.2x and below are affected by this issue. However OpenSSL 1.0.2 is out of support and no longer receiving public updates. Premium support customers of OpenSSL 1.0.2 should upgrade to 1.0.2y. Other users should upgrade to 1.1.1j. Fixed in OpenSSL 1.1.1j (Affected 1.1.1-1.1.1i). Fixed in OpenSSL 1.0.2y (Affected 1.0.2-1.0.2x).

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
How this class of weakness works · CWE-190

An arithmetic operation produces a value too large for its type and wraps around to an unexpected — often tiny or negative — number. That miscalculated value then drives a memory allocation or a bounds check, opening the door to corruption. The fix is checked arithmetic and validating sizes before they're used.

General guidance for the integer overflow class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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
OpenSSLFramework / library
Affected:>= 1.0.2, < 1.0.2y>= 1.1.1, < 1.1.1j
Debian LinuxOperating system
Affected:= 10.0
Node.jsApplication
Affected:>= 10.0.0, <= 10.12.0>= 10.13.0, < 10.24.0>= 12.0.0, <= 12.12.0>= 12.13.0, < 12.21.0>= 14.0.0, <= 14.14.0>= 15.0.0, < 15.10.0= 14.15.0
Log Correlation EngineApplication
Affected:< 6.0.8
Nessus Network MonitorApplication
Affected:= 5.11.0= 5.11.1= 5.12.0= 5.12.1= 5.13.0
Business IntelligenceApplication
Affected:= 5.5.0.0.0= 5.9.0.0.0= 12.2.1.3.0= 12.2.1.4.0
Communications Cloud Native Core PolicyApplication
Affected:= 1.15.0
Enterprise Manager For Storage ManagementApplication
Affected:= 13.4.0.0

CVSS 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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 data
Upgrade available Upgrade to 1.0.2y / 1.1.1j / 6.0.8 or later
Fixed in 1.0.2y1.1.1j6.0.8
Vendor patch www.oracle.com →
We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,200. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-23840 in production — separate from our analysis above.

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What this is

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  • Version or environment caveats, and links to real fixes
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