CVE-2026-4786: Python2.7 · Mitgation of CVE-2026-4519 was incomplete
Affects python2.7Source GCVE Database
Mentioned vulnerabilities
Not known to be exploited · CVSS 7.0 High · fixed in 3.10.12-1~22.04.16 : patch python2.7 soon.
Data as of 9 Nov 2026, 14:22 UTC
- Patch
- Available – fixed in 3.10.12-1~22.04.16, 3.12.3-1ubuntu0.15, 3.14.4-1ubuntu0.1
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 13 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.
What to do
Upgrade the Ubuntu to 3.10.12-1~22.04.16 (python3.10 package) or 3.12.3-1ubuntu0.15 (python3.12 package) or 3.14.4-1ubuntu0.1 (python3.14 package).
Patches and advisories
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10jythonpkg:deb/ubuntu/jython?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10pypy3pkg:deb/ubuntu/pypy3?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSpypy3pkg:deb/ubuntu/pypy3?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSpython3.14pkg:deb/ubuntu/python3.14?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 25.10jythonpkg:deb/ubuntu/jython?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10pypy3pkg:deb/ubuntu/pypy3?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available and users should update to the patched versions of Python packages as provided by Ubuntu security notices, specifically versions 3.10.12-1~22.04.16, 3.12.3-1ubuntu0.15, and 3.14.4-1ubuntu0.1 or later. Applying these official updates will remediate the vulnerability. Standard system updates will apply the necessary patches. No additional mitigation actions are indicated by the vendor advisory.
Description
CVE-2026-4786 is a vulnerability in Python 2.7 where the mitigation for a previous flaw (CVE-2026-4519) was incomplete. Specifically, if a URL contained "%action", certain browser types could bypass the mitigation, allowing command injection via the webbrowser.open() API into the underlying shell. This vulnerability affects multiple Python 2.7 versions and some Python 3 versions prior to fixed releases. A high-severity CVSS 3.1 score of 7.1 has been assigned. Official patches are available in updated Ubuntu package versions.
References
- ubuntu.com/security/CVE-2026-4786 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-4786 (opens in a new tab)
- mail.python.org/archives/list/security-announce@python.org/thread/JQDUNJVB4AQNTJECSUKOBDU3XCJIPSE5/ (opens in a new tab)
- github.com/python/cpython/pull/148170 (opens in a new tab)
- ubuntu.com/security/notices/USN-8509-1 (opens in a new tab)