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Vulnerability details: VCID-dt7c-fvqj-2bek
Vulnerability ID VCID-dt7c-fvqj-2bek
Aliases CVE-2026-27448
GHSA-vp96-hxj8-p424
Summary pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback If a user provided callback to `set_tlsext_servername_callback` raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Unhandled exceptions now result in rejecting the connection. Credit to **Leury Castillo** for reporting this issue.
Status Published
Exploitability 0.5
Weighted Severity 4.9
Risk 2.5
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-636 Not Failing Securely ('Failing Open')
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3 5.4 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-27448.json
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00041 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00041 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00041 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00041 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00041 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00041 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
epss 0.00041 https://api.first.org/data/v1/epss?cve=CVE-2026-27448
cvssv3.1 3.7 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv3.1_qr LOW https://github.com/advisories/GHSA-vp96-hxj8-p424
cvssv4 1.7 https://github.com/pyca/pyopenssl
generic_textual LOW https://github.com/pyca/pyopenssl
cvssv4 1.7 https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27
generic_textual LOW https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27
ssvc Track https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27
cvssv4 1.7 https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0
generic_textual LOW https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0
ssvc Track https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0
cvssv3.1_qr LOW https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424
cvssv4 1.7 https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424
generic_textual LOW https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424
ssvc Track https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424
cvssv4 1.7 https://nvd.nist.gov/vuln/detail/CVE-2026-27448
generic_textual LOW https://nvd.nist.gov/vuln/detail/CVE-2026-27448
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-27448.json
https://api.first.org/data/v1/epss?cve=CVE-2026-27448
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-27448
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
https://github.com/pyca/pyopenssl
https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27
https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0
https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424
https://nvd.nist.gov/vuln/detail/CVE-2026-27448
2448508 https://bugzilla.redhat.com/show_bug.cgi?id=2448508
GHSA-vp96-hxj8-p424 https://github.com/advisories/GHSA-vp96-hxj8-p424
RHSA-2026:7224 https://access.redhat.com/errata/RHSA-2026:7224
USN-8115-1 https://usn.ubuntu.com/8115-1/
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-27448.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U Found at https://github.com/pyca/pyopenssl
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U Found at https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-03-18T20:17:52Z/ Found at https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U Found at https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-03-18T20:17:52Z/ Found at https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U Found at https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-03-18T20:17:52Z/ Found at https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U Found at https://nvd.nist.gov/vuln/detail/CVE-2026-27448
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.11415
EPSS Score 0.00038
Published At April 2, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-04-01T12:54:10.484446+00:00 GithubOSV Importer Import https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-vp96-hxj8-p424/GHSA-vp96-hxj8-p424.json 38.0.0