CVE-2024-13176Network attack vector

Private-key recovery via variable-top nonce inversion

Published Jan 20, 2025 · Updated Mar 18, 2026

Covert timing channel in OpenSSL ECDSA signing allows attackers to recover private keys by measuring signature timing. The ec_field_inverse_mod_ord path used a variable-top BIGNUM result for nonce inversion, making operations about 300 nanoseconds faster when its top word was zero. Exploitation requires P-521 signing and either a process on the same physical computer or a very fast, low-latency network connection; FIPS modules in 3.0 through 3.4 are affected.

CVSS severity4.1
Medium
EPSS probability0.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Covert timing channel in OpenSSL ECDSA signing allows attackers to recover private keys by measuring signature timing. The ec_field_inverse_mod_ord path used a variable-top BIGNUM result for nonce inversion, making operations about 300 nanoseconds faster when its top word was zero. Exploitation requires P-521 signing and either a process on the same physical computer or a very fast, low-latency network connection; FIPS modules in 3.0 through 3.4 are affected.

The record

CVE
CVE-2024-13176
Published
Jan 20, 2025
Updated
Mar 18, 2026
Vendor
OpenSSL Project
Product
OpenSSL
Classifications
CWE-385, T1552.004
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Jan 20, 2025CVE publishedPublication date reported by the CVE source.
  2. Mar 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0.2 <1.0.2zl
  2. Affected versionversion=1.1.1 <1.1.1zb
  3. Affected versionversion=3.0.0 <3.0.16
  4. Affected versionversion=3.1.0 <3.1.8
  5. Affected versionversion=3.2.0 <3.2.4
  6. Affected versionversion=3.3.0 <3.3.3
  7. Affected versionversion=3.4.0 <3.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

OpenSSL Project · OpenSSLversion=1.0.2 <1.0.2zl; version=1.1.1 <1.1.1zb; version=3.0.0 <3.0.16; version=3.1.0 <3.1.8; version=3.2.0 <3.2.4; version=3.3.0 <3.3.3; version=3.4.0 <3.4.1

Published CVSS scores

4.1CISA-ADPCVSS:3.1/AV:P/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

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)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-385Covert Timing Channel
T1552.004Unsecured Credentials: Private Keys

Public exploit references

No public exploit references are available in this record.

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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