CVE-2026-19553: SSLContext.wrap_bio() missing validation of server_hostname parameter
Noroxi assessment
Priority: Monitor (action score 30/100)
- Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.54% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No special conditions are required; it is repeatable.
- Fixed version: Python Software Foundation CPython 3.10.22, 3.11.17, 3.12.15; azl3 python3 3.12.14-2 on Azure Linux 3.0 3.12.15-1.
Low priority for now. Upgrade to Python Software Foundation CPython 3.10.22, 3.11.17, 3.12.15; azl3 python3 3.12.14-2 on Azure Linux 3.0 3.12.15-1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
ssl.SSLContext.wrap_bio() didn't require the server_hostname argument to not be None if ssl.SSLContext.check_hostname was set. Due to a missing parameter check in SSLObject, if the server_hostname argument isn't supplied then hostname verification would be silently skipped. This defect could lead to programs where certificate hostname verification *appeared* to be succeeding with SSLContext.check_hostname = True and no ValueError being raised due to misconfiguration. If the program passes a server_hostname value that isn't an empty string or None to any of these APIs then certificate hostname verification proceeds as expected and the program is not affected by this vulnerability. Mitigating this vulnerability doesn't require updating Python or applying the patch. To mitigate, pass a valid non-None and non-empty server_hostname value to SSLContext.wrap_bio(), asyncio.create_connection(), or asyncio.loop.start_tls() and certificate hostname verification will proceed as expected. Upgrading to the latest version of Python or applying the patch only changes the behavior from silently skipping hostname verification to raising a ValueError, similar to SSLContext.wrap_socket(), when server_hostname isn't supplied.
- EUVD-2026-90078
- ALSA-2026:77017
- ALSA-2026:77018
- ALSA-2026:77020
- ALSA-2026:77021
- ALSA-2026:77028
- ALSA-2026:85239
- ALSA-2026:89742
- openSUSE-SU-2026:12069-1
- openSUSE-SU-2026:12087-1
- openSUSE-SU-2026:12121-1
- openSUSE-SU-2026:12122-1
- openSUSE-SU-2026:12123-1
- openSUSE-SU-2026:12124-1
- RHSA-2026:74587
- RHSA-2026:74594
- RHSA-2026:74599
- RHSA-2026:74605
- RHSA-2026:74606
- RHSA-2026:77017
- Published
- Sep 30, 2026
- Updated
- Nov 10, 2026
- EPSS
- 0.5% · 46th percentile
- CWE
- CWE-297
Report tools
Action score
30
Low priority for now.
- CVSS
- 30 / 40 · 7.6 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.5%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · PSF
- 7.6
- NVD has not scored this yet; the score shown is the CNA’s.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- Proof of concept exists, no weaponized module
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
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Is your version affected?
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Run the SSL checkVersions reported by the vendor
Affected version ranges reported by the assigning authority (PSF). Independent of NVD's CPE analysis and usually ahead of it.
Python Software Foundation CPython
- before 3.10.22affected · python
- 3.11.0 and later · before 3.11.17affected · python
- 3.12.0 and later · before 3.12.15affected · python
- 3.13.0 and later · before 3.13.16affected · python
- 3.14.0 and later · before 3.14.8affected · python
- 3.15.0a1 and later · before 3.15.0rc3affected · python
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:10 | python-unversioned-command | before 3.12.15-1.el10_2 | 3.12.15-1.el10_2 |
| AlmaLinux:10 | python3 | before 3.12.15-1.el10_2 | 3.12.15-1.el10_2 |
| AlmaLinux:10 | python3-debug | before 3.12.15-1.el10_2 | 3.12.15-1.el10_2 |
| AlmaLinux:10 | python3-devel | before 3.12.15-1.el10_2 | 3.12.15-1.el10_2 |
| AlmaLinux:10 | python3-idle | before 3.12.15-1.el10_2 | 3.12.15-1.el10_2 |
| AlmaLinux:10 | python3-libs | before 3.12.15-1.el10_2 | 3.12.15-1.el10_2 |
| AlmaLinux:10 | python3-test | before 3.12.15-1.el10_2 | 3.12.15-1.el10_2 |
| AlmaLinux:10 | python3-tkinter | before 3.12.15-1.el10_2 | 3.12.15-1.el10_2 |
| AlmaLinux:10 | python3.14 | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-debug | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-devel | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading-debug | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading-devel | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading-idle | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading-libs | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading-test | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-freethreading-tkinter | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-idle | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-libs | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-test | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:10 | python3.14-tkinter | before 3.14.8-1.el10_2 | 3.14.8-1.el10_2 |
| AlmaLinux:8 | platform-python | before 3.6.8-79.el8_10.alma.1 | 3.6.8-79.el8_10.alma.1 |
| AlmaLinux:8 | platform-python-debug | before 3.6.8-79.el8_10.alma.1 | 3.6.8-79.el8_10.alma.1 |
+96
Same product
python software foundation: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-115557Distrust compromised intermediate certificates in ssl module37Monitor
- CVE-2025-4517Arbitrary writes via tarfile realpath overflow37Monitor
- CVE-2026-19445Use-after-free of a server-side SSLContext when sni_callback switches contexts36Monitor
Published before and after this one in the same product
- ← EarlierCVE-2026-82049Sep 14, 2026 · tarfile extraction filters allow file modification and content disclosure via hard link to symlink33Monitor
- ← EarlierCVE-2026-12345Sep 29, 2026 · Race condition in tempfile.TemporaryDirectory cleanup allows deleting files outside the temporary directory23Monitor
- Later →CVE-2026-114583Oct 22, 2026 · tar filter allows writing outside destination via empty-named symlink27Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Python Software Foundation CPython | 3.10.22 | Vendor (CNA) |
| Python Software Foundation CPython | 3.11.17 | Vendor (CNA) |
| Python Software Foundation CPython | 3.12.15 | Vendor (CNA) |
| Python Software Foundation CPython | 3.13.16 | Vendor (CNA) |
| Python Software Foundation CPython | 3.14.8 | Vendor (CNA) |
| Python Software Foundation CPython | 3.15.0rc3 | Vendor (CNA) |
| azl3 python3 3.12.14-2 on Azure Linux 3.0 | 3.12.15-1 · Release Notes | Microsoft (MSRC) |
| almalinux:python3.12 | 3.12.15-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.12 | 3.12.15-2.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python3.12-debug | 3.12.15-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.12-debug | 3.12.15-2.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python3.12-devel | 3.12.15-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.12-devel | 3.12.15-2.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python3.12-idle | 3.12.15-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.12-idle | 3.12.15-2.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python3.12-libs | 3.12.15-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.12-libs | 3.12.15-2.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python3.12-rpm-macros | 3.12.15-2.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python3.12-test | 3.12.15-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.12-test | 3.12.15-2.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python3.12-tkinter | 3.12.15-1.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:python3.12-tkinter | 3.12.15-2.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python3.14 | 3.14.8-1.el10_2 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:python3.14-debug | 3.14.8-1.el10_2 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:python3.14-devel | 3.14.8-1.el10_2 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:python3.14-freethreading | 3.14.8-1.el10_2 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:python3.14-freethreading-debug | 3.14.8-1.el10_2 · AlmaLinux:10 | Package registry (OSV) |
| alpine:python3 | 3.12.15-r0 · Alpine:v3.21 | Package registry (OSV) |
| debian:pypy3 | 8.0.1+dfsg-1 · Debian:14 | Package registry (OSV) |
| debian:python3.11 | 3.11.2-6+deb12u9 · Debian:12 | Package registry (OSV) |
+36
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Proof-of-concept repository on GitHub ×3
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | 3 repositories | 2026-10-02 → 2026-11-08 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Published
- Fix recordedsame day
- First PoC+1 d
- TodayNov 13, 2026+44 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- devdanzin (https://github.com/devdanzin)reporter
- Bhuvansh (https://github.com/BHUVANSH855)analyst
- Bénédikt Tran (https://github.com/picnixz)remediation reviewer
- Seth Larson (https://github.com/sethmlarson)coordinator
Not on record for this CVE: variant or chain candidate · public bounty program.
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- Integrity
- Availability
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- P
- Scope
- X
Weakness class (CWE)
CWE-297 · Improper Validation of Certificate with Host MismatchCVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- SSVC exploitation— → none
- Exploit maturitynone → poc
- Exploit maturity— → none
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (11 more)Show less
- github.com/python/cpython/commit/5867d4e4ae6d1062352baf6b497a4026e8578ccf
- github.com/python/cpython/commit/641390146a16a38e6701923f4ee4f1940ae77082
- github.com/python/cpython/commit/869069d52ce0efab2f8c38197e92cdaaa312f1ed
- github.com/python/cpython/commit/966bf426d0b6c31c1b0a255ff14a17143a466ced
- github.com/python/cpython/commit/bdebbf9b366ec91e9cd9daa0b3510c9e84b60b80
- github.com/python/cpython/commit/f4e43ba525187282f2011da0e6ffc0d2b08d8062
- github.com/python/cpython/issues/156793
- github.com/python/cpython/pull/158503
- mail.python.org/archives/list/security-announce@python.org/thread/QNZRG3YOAMTHDCMVCICXGY6YEFPY2VDL/
- www.openwall.com/lists/oss-security/2026/09/30/16
- cert-portal.siemens.com/productcert/html/ssa-457936.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.