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Vulnerability record · CVE-2026-32884 · published 30 March 2026

CVE-2026-32884: Botan project botan improper certificate validation vulnerability

Botan Project · Botan

Botan is a C++ cryptography library. Prior to version 3.11.0, during processing of an X.509 certificate path using name constraints which restrict the set of allowable DNS names, if no subject alternative name is defined in the end-entity certificate Botan would check that the CN was allowed by the DNS name constraints, even though this check is technically not required by RFC 5280. However this check failed to account for the possibility of a mixed-case CN. Thus a certificate with CN=Sub.EVIL.COM and no subject alternative name would bypasses an excludedSubtrees constraint for evil.com because the comparison is case-sensitive. This issue has been patched in version 3.11.0.

5.9 CVSS 3.1 Medium EPSS 0.20% · top 91.6% CWE-295 · Improper certificate validation
5.9CVSS 3.1 base score
0.20%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
1References
17 Jun 2026Last modified by NVD

Description

Botan is a C++ cryptography library. Prior to version 3.11.0, during processing of an X.509 certificate path using name constraints which restrict the set of allowable DNS names, if no subject alternative name is defined in the end-entity certificate Botan would check that the CN was allowed by the DNS name constraints, even though this check is technically not required by RFC 5280. However this check failed to account for the possibility of a mixed-case CN. Thus a certificate with CN=Sub.EVIL.COM and no subject alternative name would bypasses an excludedSubtrees constraint for evil.com because the comparison is case-sensitive. This issue has been patched in version 3.11.0.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/randombit/botan/security/advisories/GHSA-7c3g-7763-ggj5 Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2021-24115Botan project botan vulnerabilityIn Botan before 2.17.3, constant-time computations are not used for certain decoding and encoding operations (base32, base58, base64, and hex).EPSS 2.0%9.8CVE-2018-9127Botan project botan improper certificate validation vulnerabilityBotan 2.2.0 - 2.4.0 (fixed in 2.5.0) improperly handled wildcard certificates and could accept certain certificates as valid for hostnames when, unde…EPSS 0.93%9.8CVE-2017-2801Botan project botan out-of-bounds read vulnerabilityA programming error exists in a way Randombit Botan cryptographic library version 2.0.1 implements x500 string comparisons which could lead to certif…EPSS 1.3%9.8CVE-2015-7826Botan project botan improper certificate validation vulnerabilitybotan 1.11.x before 1.11.22 improperly handles wildcard matching against hostnames, which might allow remote attackers to have unspecified impact via…EPSS 1.1%9.8CVE-2016-6878Botan project botan improper input validation vulnerabilityThe Curve25519 code in botan before 1.11.31, on systems without a native 128-bit integer type, might allow attackers to have unspecified impact via v…EPSS 1.2%9.8CVE-2016-9132Botan project botan integer overflow vulnerabilityIn Botan 1.8.0 through 1.11.33, when decoding BER data an integer overflow could occur, which would cause an incorrect length field to be computed. S…EPSS 2.0%9.8CVE-2016-2196Botan project botan memory buffer overflow vulnerabilityHeap-based buffer overflow in the P-521 reduction function in Botan 1.11.x before 1.11.27 allows remote attackers to cause a denial of service (memor…EPSS 5.3%9.8CVE-2016-2195Botan project botan memory buffer overflow vulnerabilityInteger overflow in the PointGFp constructor in Botan before 1.10.11 and 1.11.x before 1.11.27 allows remote attackers to overwrite memory and possib…EPSS 6.7%

Source: NIST National Vulnerability Database (record CVE-2026-32884), CISA KEV, FIRST EPSS (scores of 2026-09-30). This page is refreshed as NVD updates the record.