CVE-2020-25657Public exploitNetwork attack vector

Plaintext recovery via RSA decryption timing oracle

Published Jan 12, 2021 · Updated Aug 4, 2024

Timing side channel in M2Crypto's RSA decryption API allows remote attackers to recover PKCS#1 v1.5 plaintext through oracle queries. rsa_private_decrypt follows measurably different error-handling paths for conforming and nonconforming ciphertext, exposing a padding oracle. Exploitation requires repeated chosen-ciphertext queries and precise timing measurements against an application that exposes the API, and yields message plaintext without integrity or availability impact.

CVSS severity5.9
Medium
EPSS probability1.74%
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 M2Crypto's RSA decryption API allows remote attackers to recover PKCS#1 v1.5 plaintext through oracle queries. rsa_private_decrypt follows measurably different error-handling paths for conforming and nonconforming ciphertext, exposing a padding oracle. Exploitation requires repeated chosen-ciphertext queries and precise timing measurements against an application that exposes the API, and yields message plaintext without integrity or availability impact.

The record

CVE
CVE-2020-25657
Published
Jan 12, 2021
Updated
Aug 4, 2024
Vendor
M2Crypto Project
Product
M2Crypto
Classifications
CWE-385, CWE-203, T1040
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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=All released versions of m2crypto

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

M2Crypto Project · M2Cryptoversion=All released versions of m2crypto

Published CVSS scores

5.9NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
4.3NVDAV:N/AC:M/Au:N/C:P/I:N/A:N
7.5SUSECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A: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.

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-385Covert Timing Channel
CWE-203Observable Discrepancy
T1040Network Sniffing

Public exploit references

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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