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CVE-2021-43398

20
FAUCET Score

CVE-2021-43398 describes a timing leakage vulnerability in Crypto++ (aka Cryptopp) versions 8.6.0 and earlier, specifically within the MakePublicKey() function. This flaw allows an attacker to infer the private key length by observing execution times, potentially enabling timing attacks. The vulnerability is rated Medium severity (CVSS 5.3), indicating a low-complexity network attack that could lead to limited confidentiality impact. Despite the vendor disputing its practical exploitability due to intentional design choices, there is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
<= 8.6.0CPE matchmatch criteria
cpe:2.3:a:cryptopp:crypto\+\+:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.3MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.90%
Probability of exploitation in next 30 days
EPSS Percentile
77.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0190 is in the 65th percentile among its peer group of 23,705 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

cryptopp.com
Vendor Advisory
github.com / weidai11/cryptopp/issues/1080
ExploitThird Party Advisory
github.com / weidai11/cryptopp/issues/1080
ExploitIssue TrackingThird Party Advisory