CVE-2026-4786

NameCVE-2026-4786
DescriptionMitgation of CVE-2026-4519 was incomplete. If the URL contained "%action" the mitigation could be bypassed for certain browser types the "webbrowser.open()" API could have commands injected into the underlying shell. See CVE-2026-4519 for details.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
jython (PTS)bullseye2.7.2+repack1-3fixed
forky, sid, bookworm, trixie2.7.3+repack1-1fixed
pypy3 (PTS)bullseye7.3.5+dfsg-2+deb11u2fixed
bullseye (security)7.3.5+dfsg-2+deb11u5fixed
bookworm7.3.11+dfsg-2+deb12u3fixed
trixie7.3.19+dfsg-2fixed
forky, sid7.3.22+dfsg-1fixed
python2.7 (PTS)bullseye2.7.18-8+deb11u1fixed
python3.11 (PTS)bookworm3.11.2-6+deb12u7fixed
bookworm (security)3.11.2-6+deb12u3fixed
python3.13 (PTS)trixie3.13.5-2+deb13u2fixed
forky, sid3.13.12-1vulnerable
python3.14 (PTS)forky, sid3.14.5-1fixed
python3.9 (PTS)bullseye3.9.2-1fixed
bullseye (security)3.9.2-1+deb11u7fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
jythonsource(unstable)(not affected)
pypy3sourcebullseye(not affected)
pypy3sourcebookworm(not affected)
pypy3sourcetrixie(not affected)
pypy3source(unstable)7.3.22+dfsg-1
python2.7source(unstable)(not affected)
python3.11source(unstable)(not affected)
python3.13sourcetrixie(not affected)
python3.13source(unstable)(unfixed)
python3.14source(unstable)3.14.5-1
python3.9source(unstable)(not affected)

Notes

[trixie] - python3.13 <not-affected> (Incomplete fix not released)
- python3.11 <not-affected> (Incomplete fix not released)
- python3.9 <not-affected> (Incomplete fix not released)
- python2.7 <not-affected> (Incomplete fix not released)
- jython <not-affected> (Incomplete fix not released)
[trixie] - pypy3 <not-affected> (Incomplete fix not released)
[bookworm] - pypy3 <not-affected> (Incomplete fix not released)
[bullseye] - pypy3 <not-affected> (Incomplete fix not released)
Incomplete fix for CVE-2026-4519, followup fixes listed there:
https://mail.python.org/archives/list/security-announce@python.org/thread/JQDUNJVB4AQNTJECSUKOBDU3XCJIPSE5/
https://github.com/python/cpython/issues/148169
https://github.com/python/cpython/pull/148170
https://github.com/python/cpython/commit/28b4ad38067bbdad34edfcd03ad2de5f06387e53 (v3.14.5rc1)

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