CVE-2025-12888

Key disclosure via Xtensa X25519 timing leakage

Published Nov 21, 2025 · Updated Nov 21, 2025

Timing side channel in wolfSSL before 5.8.4 allows physically proximate attackers to derive X25519 key material on Xtensa-based ESP32 chips. Xtensa compiler output converts the intended constant-time X25519 path into data-dependent assembly, so execution time varies with secret values. Repeated physical timing measurements and low-privileged device access are required; the result is indirect disclosure of cryptographic secrets.

CVSS severity1.0
Low
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Timing side channel in wolfSSL before 5.8.4 allows physically proximate attackers to derive X25519 key material on Xtensa-based ESP32 chips. Xtensa compiler output converts the intended constant-time X25519 path into data-dependent assembly, so execution time varies with secret values. Repeated physical timing measurements and low-privileged device access are required; the result is indirect disclosure of cryptographic secrets.

The record

CVE
CVE-2025-12888
Published
Nov 21, 2025
Updated
Nov 21, 2025
Vendor
wolfSSL
Product
wolfSSL
Classifications
CWE-203, CAPEC-485
Attack vector
physical
Privileges
Unavailable

Timeline

How it unfolded

  1. Nov 21, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 21, 2025Record 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=5.8.2

What conditions does exploitation require?

Attack vectorphysical
Required privilegesUnavailable in this record.

What is affected?

wolfSSL · wolfSSLversion=5.8.2

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
1.0wolfSSL Inc.CVSS:4.0/AV:P/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:L/SA:N

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)
Vectorphysical
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-203Observable Discrepancy
CAPEC-485Signature Spoofing by Key Recreation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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