ZDF
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2026-19553

ssl.SSLContext.wrap_bio() didn't require the server_hostname argument to not be None if ssl.SSLContext.check_hostname was set.

Published Sep 30, 2026 · catalog updated Oct 28, 2026 · BSI

Last checked Oct 29, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-19553. EPSS is 0.55%. Act only if a listed version of BSI is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Unknown—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.55%
Remediation
Advisory link
Affected products
Debian:12 pypy3 · Debian:12 python3.11 · Debian:13 pypy3 · Debian:13 python3.13 · Debian:14 pypy3 · Debian:14 python3.13

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Debian:12 pypy37.3.11+dfsg-2, 7.3.11+dfsg-2+deb12u1, 7.3.11+dfsg-2+deb12u2
  • Debian:12 python3.110 → 3.11.2-6+deb12u9
  • Debian:13 pypy37.3.19+dfsg-2, 7.3.20+dfsg-1, 7.3.20+dfsg-2
  • Debian:13 python3.133.13.11-1, 3.13.12-1, 3.13.14-1
  • Debian:14 pypy30 → 8.0.1+dfsg-1
  • Debian:14 python3.133.13.11-1, 3.13.12-1, 3.13.14-1
  • Debian:14 python3.140 → 3.14.8-1
  • Debian:14 python3.150 → 3.15.0~rc3-1

How to fix CVE-2026-19553

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-19553. EPSS is 0.55%. Act only if a listed version of BSI is installed.

Which versions are affected?

Compare what you have installed with 7.3.11+dfsg-2, 7.3.11+dfsg-2+deb12u1, 7.3.11+dfsg-2+deb12u2, 0 → 3.11.2-6+deb12u9, 7.3.19+dfsg-2, 7.3.20+dfsg-1, 7.3.20+dfsg-2, 3.13.11-1, 3.13.12-1, 3.13.14-1, 0 → 8.0.1+dfsg-1, 0 → 3.14.8-1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.55%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 26, 2026 · BSI CERT-Bund

    Detected

    CVE-2026-19553 is listed by CPython: Mehrere Schwachstellen.

  2. Oct 28, 2026 · Trivy Vulnerability DB

    Fix available

    pypy3 fixed in 8.0.1+dfsg-1; python3.11 fixed in 3.11.2-6+deb12u9; python3.14 fixed in 3.14.8-1; python3.15 fixed in 3.15.0~rc3-1

  3. Oct 28, 2026 · Trivy Vulnerability DB

    Fix available

    pypy3 fixed in 8.0.1+dfsg-1

  4. Oct 28, 2026 · Trivy Vulnerability DB

    Fix available

    python3.11 fixed in 3.11.2-6+deb12u9

  5. Oct 28, 2026 · Trivy Vulnerability DB

    Fix available

    python3.14 fixed in 3.14.8-1

  6. Oct 28, 2026 · Trivy Vulnerability DB

    Fix available

    python3.15 fixed in 3.15.0~rc3-1

  7. Oct 28, 2026 · Trivy Vulnerability DB

    Updated

    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_

Sources

  • BSI CERT-BundGovernment advisoryCVE-2026-19553

    CPython: Mehrere Schwachstellen

    wid.cert-bund.de
  • CVE.orgVulnerability recordCVE-2026-19553

    Official CVE identifier

    cve.org
  • Trivy Vulnerability DBPackage advisoryDEBIAN-CVE-2026-19553

    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

    osv.dev

References

Freshness

Last verified in this catalog Oct 29, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • Trivy Vulnerability DBOct 28, 2026
  • BSI CERT-BundOct 27, 2026
  • CVE.orgOct 26, 2026