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CVE-2025-12888

Constant Time Issue with Xtensa-based ESP32 and X22519

1.0 LowFix available

Vulnerability in X25519 constant-time cryptographic implementations due to timing side channels introduced by compiler optimizations and CPU architecture limitations, specifically with the Xtensa-based ESP32 chips. If targeting Xtensa it is recommended to use the low memory implementations of X25519, which is now turned on as the default for Xtensa.

Attack profile

How easy it is to exploit

Attack vector
Physical
Complexity
High
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
None
Availability
None

Exploit likelihood

0.31%Up 0.3 points since Nov 22, 2025
90%50%10%1%

What each source reports

CVE List Score used 1.0

Constant Time Issue with Xtensa-based ESP32 and X22519

Vulnerability in X25519 constant-time cryptographic implementations due to timing side channels introduced by compiler optimizations and CPU architecture limitations, specifically with the Xtensa-based ESP32 chips. If targeting Xtensa it is recommended to use the low memory implementations of X25519, which is now turned on as the default for Xtensa.

Record
CVE-2025-12888
CVSS 4.0
1.0 LowCVSS:4.0/AV:P/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:L/SA:N
Weakness
CWE-203
Updated
2026-11-02
EUVDEUVD-2025-198523 1.0

Vulnerability in X25519 constant-time cryptographic implementations due to timing side channels introduced by compiler optimizations and CPU architecture limitations, specifically with the Xtensa-based ESP32 chips. If targeting Xtensa it is recommended to use the low memory implementations of X25519, which is now turned on as the default for Xtensa.

Record
EUVD-2025-198523
CVSS 4.0
1.0 LowCVSS:4.0/AV:P/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:L/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-xmgq-3783-qgm4 1.0

Vulnerability in X25519 constant-time cryptographic implementations due to timing side channels...

Vulnerability in X25519 constant-time cryptographic implementations due to timing side channels introduced by compiler optimizations and CPU architecture limitations, specifically with the Xtensa-based ESP32 chips. If targeting Xtensa it is recommended to use the low memory implementations of X25519, which is now turned on as the default for Xtensa.

Record
GHSA-xmgq-3783-qgm4
CVSS 4.0
1.0 LowCVSS:4.0/AV:P/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-203
Updated
2026-11-02
NVD 1.0

Vulnerability in X25519 constant-time cryptographic implementations due to timing side channels introduced by compiler optimizations and CPU architecture limitations, specifically with the Xtensa-based ESP32 chips. If targeting Xtensa it is recommended to use the low memory implementations of X25519, which is now turned on as the default for Xtensa.

Record
CVE-2025-12888
CVSS 4.0
1.0 LowCVSS:4.0/AV:P/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-203
Updated
2026-11-02
OSVALPINE-CVE-2025-12888 7.5

Vulnerability in X25519 constant-time cryptographic implementations due to timing side channels introduced by compiler optimizations and CPU architecture limitations, specifically with the Xtensa-based ESP32 chips. If targeting Xtensa it is recommended to use the low memory implementations of X25519, which is now turned on as the default for Xtensa.

Record
ALPINE-CVE-2025-12888
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-03
OSV 1.0

Constant Time Issue with Xtensa-based ESP32 and X22519

Vulnerability in X25519 constant-time cryptographic implementations due to timing side channels introduced by compiler optimizations and CPU architecture limitations, specifically with the Xtensa-based ESP32 chips. If targeting Xtensa it is recommended to use the low memory implementations of X25519, which is now turned on as the default for Xtensa.

Record
CVE-2025-12888
CVSS 4.0
1.0 LowCVSS:4.0/AV:P/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:L/SA:N
Weakness
CWE-203
Updated
2026-11-02
OSVDEBIAN-CVE-2025-12888 7.5

Vulnerability in X25519 constant-time cryptographic implementations due to timing side channels introduced by compiler optimizations and CPU architecture limitations, specifically with the Xtensa-based ESP32 chips. If targeting Xtensa it is recommended to use the low memory implementations of X25519, which is now turned on as the default for Xtensa.

Record
DEBIAN-CVE-2025-12888
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVUBUNTU-CVE-2025-12888 1.0

Vulnerability in X25519 constant-time cryptographic implementations due to timing side channels introduced by compiler optimizations and CPU architecture limitations, specifically with the Xtensa-based ESP32 chips. If targeting Xtensa it is recommended to use the low memory implementations of X25519, which is now turned on as the default for Xtensa.

Record
UBUNTU-CVE-2025-12888
CVSS 4.0
1.0 LowCVSS: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 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
wolfssl
Alpine:v3.23
 before 5.9.1-r0
5.9.1-r0
wolfssl
Alpine:v3.24
 before 5.8.4-r0
5.8.4-r0
wolfssl
Debian:12
 All versions, plus listed versions
5.5.4-25.5.4-2+deb12u15.5.4-2+deb12u25.5.4-2+deb12u35.5.4-2.1
Show 24 moreShow less
5.6.4-15.6.4-25.6.6-15.6.6-1.15.6.6-1.25.6.6-1.35.6.6-1.3~exp15.7.0-0.15.7.0-0.25.7.0-0.35.7.2-0.15.7.2-0.25.7.2-0.35.7.2-0.45.8.2-15.8.2-1.15.8.2-1.25.8.4-15.9.0-0.15.9.0-0.25.9.1-0.15.9.2-15.9.2-1.15.9.2-1.2
 None known
wolfssl
Debian:13
 All versions, plus listed versions
5.7.2-0.15.7.2-0.1+deb13u15.7.2-0.1+deb13u25.7.2-0.25.7.2-0.3
Show 11 moreShow less
5.7.2-0.45.8.2-15.8.2-1.15.8.2-1.25.8.4-15.9.0-0.15.9.0-0.25.9.1-0.15.9.2-15.9.2-1.15.9.2-1.2
 None known
wolfssl
Ubuntu:16.04:LTS
 All versions, plus listed versions
3.4.8+dfsg-1
 None known
wolfssl
Ubuntu:18.04:LTS
 All versions, plus listed versions
3.10.2+dfsg-23.12.0+dfsg-13.12.2+dfsg-13.13.0+dfsg-1
 None known
wolfssl
Ubuntu:20.04:LTS
 All versions, plus listed versions
4.1.0+dfsg-24.2.0+dfsg-14.2.0+dfsg-24.2.0+dfsg-34.3.0+dfsg-2
 None known
wolfssl
Ubuntu:22.04:LTS
 All versions, plus listed versions
4.6.0-35.0.0-15.1.1-15.2.0-15.2.0-2
 None known
wolfssl
Ubuntu:24.04:LTS
 All versions, plus listed versions
5.5.4-25.5.4-2.15.6.4-25.6.6-1.25.6.6-1.35.6.6-1.3build1
 None known
wolfssl
Ubuntu:25.10
 All versions, plus listed versions
5.7.2-0.1
 None known
wolfssl
Ubuntu:26.10
 All versions, plus listed versions
5.9.1-0.15.9.2-1
 None known
wolfssl
Ubuntu:26.04:LTS
 All versions, plus listed versions
5.7.2-0.15.8.2-1.25.8.4-15.9.1-0.1
 None known

History

History
RecordedChangedSources
affected, aliases, facts, referencesOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-12888 is a low vulnerability (CVSS 1.0) in Wolfssl, published November 21, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.31%, the 23rd percentile. Fixed in wolfssl 5.9.1-r0.

References

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