CVE-2021-24115

Key disclosure via secret-dependent codec table lookups

Published Feb 22, 2021 · Updated Aug 3, 2024

Timing side channel in Botan before 2.17.3 allows local users to recover key material during decoding of secret-bearing data. The base32, base58, base64, and hex codecs index large decoding lookup tables with secret-dependent values, exposing cache-access patterns instead of operating in constant time. Exploitation requires local observation of shared cache resources; the documented case leaks key material while an SGX enclave parses an unencrypted PEM private key.

CVSS severity9.8
Critical
EPSS probability1.98%
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 Botan before 2.17.3 allows local users to recover key material during decoding of secret-bearing data. The base32, base58, base64, and hex codecs index large decoding lookup tables with secret-dependent values, exposing cache-access patterns instead of operating in constant time. Exploitation requires local observation of shared cache resources; the documented case leaks key material while an SGX enclave parses an unencrypted PEM private key.

The record

CVE
CVE-2021-24115
Published
Feb 22, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
Unavailable
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Feb 22, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

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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