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Fencer Vulns
medium 5.7

CVE-2026-87910 json

tarfile hardlink fallback ignores custom extraction filter rejection via None

published 2026-09-11 59 d ago modified 2026-10-29 11 d ago also BIT-libpython-2026-87910 , BIT-python-2026-87910 , BIT-python-min-2026-87910 , EUVD-2026-76162

cvss
5.7
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits
0
none known

Summary

When tarfile extracts a link on a system that doesn't support links, it falls back to extracting a member from the archive. In this case, the filter function is run twice: once for the extracted member, and once with name set to the location of the link. For one of the calls, the return value was ignored. Instead, the member should be skipped if either call returns None.

Patch / fix

  • bitnami libpython 3.10.22, 3.11.17, 3.12.15, 3.13.16, 3.14.9
  • bitnami python 3.10.22, 3.11.17, 3.12.15, 3.13.16, 3.14.9
  • bitnami python-min 3.10.22, 3.11.17, 3.12.15, 3.13.16, 3.14.9
  • Python Software Foundation CPython 3.10.22, 3.11.17, 3.12.15, 3.13.16, 3.14.9, 3.15.0rc3
  • pypy3 Debian 14 8.0.1+dfsg-1
  • python3.14 Debian 14 3.14.9-1
  • python3.15 Debian 14 3.15.0~rc3-1

debian advisories DEBIAN-CVE-2026-87910

  • python3.12 hummingbird 1 3.12.14-1.2.hum1
  • python3.12-idle hummingbird 1 3.12.14-1.2.hum1
  • python3.12-libs hummingbird 1 3.12.14-1.2.hum1
  • python3.12-test hummingbird 1 3.12.14-1.2.hum1
  • python3.12-tkinter hummingbird 1 3.12.14-1.2.hum1
  • python3.13 hummingbird 1 3.13.15-1.2.hum1
  • python3.13-idle hummingbird 1 3.13.15-1.2.hum1
  • python3.13-libs hummingbird 1 3.13.15-1.2.hum1

red hat advisories RHSA-2026:67607RHSA-2026:67606RHSA-2026:67574RHSA-2026:67575RHSA-2026:67572

  • python315 openSUSE Tumbleweed 3.15.0-1.1

opensuse advisories openSUSE-SU-2026:12125-1

  • python3 Alpine 3.23, Alpine 3.22, Alpine 3.21 3.12.15-r0

alpine advisories ALPINE-CVE-2026-87910

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python3 Azure Linux 3.0 3.12.15-1

azure linux advisories AZL-103383

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-87910 updated cvss 5.7

python: Python tarfile module: Security filter bypass allows arbitrary file write

  • Red Hat Hardened Images python3 3.14.7-1.2.hum1, python3.14 3.14.7-1.2.hum1, python3.10 3.10.21-1.2.hum1, python3.11 3.11.16-1.3.hum1, python3.12 3.12.14-1.2.hum1, python3.13 3.13.15-1.2.hum1, +27 more
    fixed: vendor fix RHSA-2026:67572
  • Red Hat Hardened Images hi/python
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
58 d ago

Exploit prediction

0.61% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 5.7 CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CNA 4.0 5.7 CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:N/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

Affected packages

ecosystem package affected fixed in
bitnami libpython
<3.10.22
>=3.11.0, <3.11.17
>=3.12.0, <3.12.15
>=3.13.0, <3.13.16
>=3.14.0, <3.14.9
3.10.22
3.11.17
3.12.15
3.13.16
3.14.9
bitnami python
<3.10.22
>=3.11.0, <3.11.17
>=3.12.0, <3.12.15
>=3.13.0, <3.13.16
>=3.14.0, <3.14.9
3.10.22
3.11.17
3.12.15
3.13.16
3.14.9
bitnami python-min
<3.10.22
>=3.11.0, <3.11.17
>=3.12.0, <3.12.15
>=3.13.0, <3.13.16
>=3.14.0, <3.14.9
3.10.22
3.11.17
3.12.15
3.13.16
3.14.9

Affected products

  • Python Software Foundation CPython

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory
  • CWE-59 Improper Link Resolution Before File Access

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.