No exploitation reportedFix available

CVE-2026-6100

Q: Is CVE-2026-6100 actively exploited?

Active exploitation of CVE-2026-6100 has not been confirmed. Its EPSS score was 0.8% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2026-6100?

CVE-2026-6100 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2026-04-13
Fixed in3.14.5 · 3.13.14 · 3.12.14 · 3.11.16 · 3.10.21
WeaknessCWE-416 · CWE-787 · CWE-825

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Use-after-free (UAF) was possible in the `lzma.LZMADecompressor`, `bz2.BZ2Decompressor`, and `gzip.GzipFile` when a memory allocation fails with a `MemoryError` and the decompression instance is re-used. This scenario can be triggered if the process is under memory pressure. The fix cleans up the dangling pointer in this specific error condition. The vulnerability is only present if the program re-uses decompressor instances across multiple decompression calls even after a `MemoryError` is raised during decompression. Using the helper functions to one-shot decompress data such as `lzma.decompress()`, `bz2.decompress()`, `gzip.decompress()`, and `zlib.decompress()` are not affected as a new decompressor instance is used per call. If the decompressor instance is not re-used after an error condition, this usage is similarly not vulnerable.

Timeline

dates in UTC

2026-04-1318:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-6100?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-6100?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV

python

Branch	Affected	Fixed in	Source
3.14	≥ 3.14.0, < 3.14.5	3.14.5	OSV
3.13	≥ 3.13.0, < 3.13.14	3.13.14	OSV
3.12	≥ 3.12.0, < 3.12.14	3.12.14	OSV
3.11	≥ 3.11.0, < 3.11.16	3.11.16	OSV
3.10	< 3.10.21	3.10.21	OSV

libpython

Branch	Affected	Fixed in	Source
3.14	≥ 3.14.0, < 3.14.5	3.14.5	OSV
3.13	≥ 3.13.0, < 3.13.14	3.13.14	OSV
3.12	≥ 3.12.0, < 3.12.14	3.12.14	OSV
3.11	≥ 3.11.0, < 3.11.16	3.11.16	OSV
3.10	< 3.10.21	3.10.21	OSV

python-min

Branch	Affected	Fixed in	Source
3.14	≥ 3.14.0, < 3.14.5	3.14.5	OSV
3.13	≥ 3.13.0, < 3.13.14	3.13.14	OSV
3.12	≥ 3.12.0, < 3.12.14	3.12.14	OSV
3.11	≥ 3.11.0, < 3.11.16	3.11.16	OSV
3.10	< 3.10.21	3.10.21	OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

platform-pythonAlmaLinux:8all versions · fixed in 3.6.8-76.el8_10.alma.1and 6 other packages
python-unversioned-commandAlmaLinux:10all versions · fixed in 3.12.12-3.el10_1.3
python3AlmaLinux:10all versions · fixed in 3.12.13-2.el10_2and 7 other packages
python3AlmaLinux:9all versions · fixed in 3.9.25-7.el9_8and 7 other packages
python3AlmaLinux:9all versions · fixed in 3.9.25-3.el9_7.3and 7 other packages
python3.11AlmaLinux:9all versions · fixed in 3.11.13-9.el9_8and 6 other packages
python3.11AlmaLinux:9all versions · fixed in 3.11.13-5.3.el9_7and 6 other packages
python3.11AlmaLinux:8all versions · fixed in 3.11.13-7.el8_10and 7 other packages

5 more package ranges on OSV.dev

Vendor advisories

CVE-2026-6100 Red Hat Product Security1,733 products fixed · 19 known affected
python: Python: Arbitrary code execution or information disclosure via use-after-free in decompression modules
python as a component of Red Hat Enterprise Linux 6 · python-devel as a component of Red Hat Enterprise Linux 6 · python-libs as a component of Red Hat Enterprise Linux 6 · +16 more
RHSA-2026:74674 Red Hat Product Security1 product fixed
Red Hat Security Advisory: Red Hat AI Base Images 3.4.3 (Neuron)
RHSA-2026:52400 Red Hat Product Security64 products fixed
Red Hat Security Advisory: python3 security update
RHSA-2026:30089 Red Hat Product Security2 products fixed
Red Hat Security Advisory: Red Hat AI Inference Server 3.3.5 (CUDA)
RHSA-2026:30088 Red Hat Product Security1 product fixed
Red Hat Security Advisory: Red Hat AI Inference Server 3.3.5 (ROCm)
RHSA-2026:30087 Red Hat Product Security3 products fixed
Red Hat Security Advisory: Red Hat AI Inference Server 3.3.5 (Spyre)

38 more advisories

Full record on NVD

Fix

Update python to 3.14.5 · 3.13.14 · 3.12.14 · 3.11.16 · 3.10.21
Vendor fix Red Hat Product Security RHSA-2026:74674 · 1 productFor more information visit https://access.redhat.com/errata/RHSA-2026:74674
Vendor fix Red Hat Product Security RHSA-2026:52400 · 64 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
Vendor fix Red Hat Product Security RHSA-2026:30089 · 2 productsFor more information visit https://access.redhat.com/errata/RHSA-2026:30089
Vendor fix Red Hat Product Security RHSA-2026:30088 · 1 productFor more information visit https://access.redhat.com/errata/RHSA-2026:30088
Vendor fix Red Hat Product Security RHSA-2026:30087 · 3 productsFor more information visit https://access.redhat.com/errata/RHSA-2026:30087
Vendor fix Red Hat Product Security RHSA-2026:30078 · 2 productsFor more information visit https://access.redhat.com/errata/RHSA-2026:30078

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVE recordread 2026-10-23
CISA-ADPSSVC decisionnone2026-04-13
OpenCVESSVC decisionnone—
CNACVSS 4.09.1read 2026-10-23
CNACVSS 3.18.1read 2026-10-23
CNAweakness (CWE)CWE-416, CWE-787, CWE-825read 2026-10-23
FIRST EPSSEPSS score0.8 %2026-10-23
OSVaffected packages—
Microsoft MSRCadvisory—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 4.0 vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/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
Published: 2026-04-13
Last Modified: 2026-08-13
NVD status: Awaiting Analysis
MSRC Title: Use-after-free in lzma.LZMADecompressor, bz2.BZ2Decompressor, and gzip.GzipFile after re-use under memory pressure

Frequently asked questions

What is CVE-2026-6100?

Is CVE-2026-6100 actively exploited?

Active exploitation of CVE-2026-6100 has not been confirmed. Its EPSS score was 0.8% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-6100?

CVE-2026-6100 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

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