CVE-2026-6100

HIGHPre-NVD 8.18.1—
EchelonGraph scoreMEDIUM confidence

Score 8.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-04-13. a secondary CVSS source baseline 8.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
8.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 8.1Exploit: None knownExposed: 0

A fix is available — apply it.

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.

CVSS v3
8.1
EG Score
8.1(medium)
EG Risk
37(Track)
EG Risk 37/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity81% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
45%
KEV
Not listed

Published

April 13, 2026

Last Modified

August 13, 2026

Advisory Details (9)

Auto-updated Jun 2, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit, github_pr.
generic

oss-security - [CVE-2026-6100] CPython: Use-after-free in lzma.LZMADecompressor, bz2.BZ2Decompressor, and gzip.GzipFile after re-use under memory pressure

http://www.openwall.com/lists/oss-security/2026/04/13/10
generic

Mailman 3 [CVE-2026-6100] Use-after-free in lzma.LZMADecompressor, bz2.BZ2Decompressor, and gzip.GzipFile after re-use under memory pressure - Security-announce - python.org

https://mail.python.org/archives/list/[email protected]/thread/HTWB2Z6KT5QQX4RYEZAFININDHNOSIF3/
github_pr

gh-148395: Fix a possible UAF in `{LZMA,BZ2,_Zlib}Decompressor`

Fix merged in python/cpython PR #148396 on 2026-04-13 — awaiting tagged release

https://github.com/python/cpython/pull/148396
generic

[CVE-2026-6100] Possible UAF in `{LZMA,BZ2,_Zlib}Decompressor` · Issue #148395 · python/cpython · GitHub

https://github.com/python/cpython/issues/148395
github_commit

commit e20c6c9667c9 (python/cpython)

Fix landed in python/cpython commit e20c6c9667c9 — awaiting tagged release

https://github.com/python/cpython/commit/e20c6c9667c99ecaab96e1a2b3767082841ffc8b
github_commit

commit c3cf71c3366f (python/cpython)

Fix landed in python/cpython commit c3cf71c3366f — awaiting tagged release

https://github.com/python/cpython/commit/c3cf71c3366fe49acb776a639405c0eea6169c20
github_commit

commit 8fc66aef6d7b (python/cpython)

Fix landed in python/cpython commit 8fc66aef6d7b — awaiting tagged release

https://github.com/python/cpython/commit/8fc66aef6d7b3ae58f43f5c66f9366cc8cbbfcd2
github_commit

commit 6a5f79c8d7bb (python/cpython)

Fix landed in python/cpython commit 6a5f79c8d7bb — awaiting tagged release

https://github.com/python/cpython/commit/6a5f79c8d7bbf22b083b240910c7a8781a59437d
github_commit

commit 47128e64f98c (python/cpython)

Fix landed in python/cpython commit 47128e64f98c — awaiting tagged release

https://github.com/python/cpython/commit/47128e64f98c3a20271138a98c2922bea2a3ee0e

Vendor Advisories for CVE-2026-6100(20)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(30)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatpython3-0:3.6.8-21.el7_9.72026-08-10redhat
redhatrhaiis/model-opt-cuda-rhel9:17823529502026-06-25redhat
redhatrhaiis/vllm-cuda-rhel9:17823528472026-06-25redhat
redhatrhaiis/vllm-rocm-rhel9:17823530932026-06-25redhat
redhatrhaiis/vllm-spyre-rhel9:17823529192026-06-25redhat
redhatpython3.11-0:3.11.2-2.el8_8.102026-06-16redhat
redhatrhaiis/model-opt-cuda-rhel9:17806819842026-06-10redhat
redhatpython3.9-0:3.9.18-3.el9_4.132026-05-28redhat
redhatrhui5/rhua-rhel9:17797982222026-05-27redhat
redhatpython3.9-0:3.9.16-1.el9_2.142026-05-20redhat
redhatpython3.9-0:3.9.10-4.el9_0.112026-05-20redhat
redhatpython3-0:3.6.8-39.el8_4.112026-05-20redhat
redhatpython3.9-0:3.9.21-2.el9_6.62026-05-20redhat
redhatpython3-0:3.6.8-51.el8_8.152026-05-20redhat
redhatpython3.14-0:3.14.4-2.el10_22026-05-19redhat
redhatpython3.12-0:3.12.13-2.el10_22026-05-19redhat
redhatpython3.12-0:3.12.13-2.el9_82026-05-19redhat
redhatpython3.9-0:3.9.25-7.el9_82026-05-19redhat
redhatpython3.11-0:3.11.13-9.el9_82026-05-19redhat
redhatpython3.14-0:3.14.4-2.el9_82026-05-19redhat
redhatpython3.12-0:3.12.1-4.el9_4.132026-05-14redhat
redhatpython3-0:3.6.8-47.el8_6.132026-05-14redhat
redhatpython3.12-0:3.12.9-2.el10_0.92026-05-13redhat
redhatpython3.11-0:3.11.11-2.el9_6.72026-05-07redhat
redhatpython3.12-0:3.12.9-1.el9_6.82026-05-07redhat
redhatpython3.11-0:3.11.7-1.el9_4.132026-05-07redhat
redhatpython3.11-0:3.11.2-2.el9_2.122026-05-05redhat
redhatrhpam-7/rhpam-smartrouter-rhel8:7.13.5-4.17773257082026-05-05redhat
redhatrhui5/rhua-tp-rhel9:17774595042026-04-29redhat
redhatpython3-0:3.6.8-76.el8_102026-04-27redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(6 across 4 ecosystems)
Debian:11(2)
PackageVulnerable rangeFixed inDependents
python2.72.7.18-10 ... 2.7.18-9 (10 versions)——
python3.93.9.2-1 ... 3.9.2-1+deb11u5 (6 versions)3.9.2-1+deb11u6—
Debian:14(2)
PackageVulnerable rangeFixed inDependents
python3.133.13.11-1 ... 3.13.9-1 (7 versions)3.13.14-1—
python3.143.14.0-1 ... 3.14.4-2 (21 versions)3.14.5~rc1-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
python3.113.11.2-6 ... 3.11.2-6+deb12u7 (8 versions)3.11.2-6+deb12u8—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
python3.133.13.5-2, 3.13.5-2+deb13u13.13.5-2+deb13u2—

Weakness Classification(3)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(20)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 5× in last 7d / 90× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 254 total refreshes for this CVE.

  1. 2026-08-30 19:17 UTCEPSS rescore
  2. 2026-08-30 01:22 UTCEPSS rescore
  3. 2026-08-28 21:42 UTCEPSS rescore
  4. 2026-08-26 14:47 UTCEPSS rescore
  5. 2026-08-25 13:49 UTCEPSS rescore
  6. 2026-08-23 00:19 UTCEPSS rescore
  7. 2026-08-21 23:49 UTCEPSS rescore
  8. 2026-08-20 22:56 UTCEPSS rescore
  9. 2026-08-19 17:04 UTCEPSS rescore
  10. 2026-08-18 13:49 UTCEPSS rescore
  11. 2026-08-18 13:49 UTCEPSS rescore
  12. 2026-08-17 13:47 UTCEPSS rescore
  13. 2026-08-16 14:56 UTCEPSS rescore
  14. 2026-08-16 14:56 UTCEPSS rescore
  15. 2026-08-16 06:53 UTCEG score recompute
  16. 2026-08-16 06:53 UTCVendor advisory
  17. 2026-08-16 06:53 UTCGHSA enrichment
  18. 2026-08-16 02:15 UTCEPSS rescore
  19. 2026-08-15 01:31 UTCEPSS rescore
  20. 2026-08-14 18:16 UTCVendor advisory
  21. 2026-08-14 18:16 UTCGHSA enrichment
  22. 2026-08-14 04:55 UTCEG score recompute
  23. 2026-08-14 04:55 UTCVendor advisory
  24. 2026-08-14 04:55 UTCGHSA enrichment
  25. 2026-08-13 22:00 UTCEPSS rescore
Show 75 more
  1. 2026-08-13 01:23 UTCEG score recompute
  2. 2026-08-13 01:23 UTCVendor advisory
  3. 2026-08-13 01:23 UTCGHSA enrichment
  4. 2026-08-13 00:41 UTCEG score recompute
  5. 2026-08-13 00:41 UTCVendor advisory
  6. 2026-08-13 00:41 UTCGHSA enrichment
  7. 2026-08-12 19:09 UTCEG score recompute
  8. 2026-08-12 19:09 UTCVendor advisory
  9. 2026-08-12 19:09 UTCGHSA enrichment
  10. 2026-08-12 13:51 UTCEPSS rescore
  11. 2026-08-11 19:16 UTCEG score recompute
  12. 2026-08-11 19:16 UTCVendor advisory
  13. 2026-08-11 19:16 UTCGHSA enrichment
  14. 2026-08-11 02:51 UTCEG score recompute
  15. 2026-08-11 02:51 UTCVendor advisory
  16. 2026-08-11 02:51 UTCGHSA enrichment
  17. 2026-08-11 00:00 UTCEPSS rescore
  18. 2026-08-10 13:23 UTCEG score recompute
  19. 2026-08-10 13:23 UTCVendor advisory
  20. 2026-08-10 13:23 UTCGHSA enrichment
  21. 2026-08-10 12:27 UTCEG score recompute
  22. 2026-08-10 12:27 UTCVendor advisory
  23. 2026-08-10 12:27 UTCGHSA enrichment
  24. 2026-08-10 03:23 UTCVendor advisory
  25. 2026-08-10 03:23 UTCGHSA enrichment
  26. 2026-08-09 15:50 UTCEG score recompute
  27. 2026-08-09 15:50 UTCVendor advisory
  28. 2026-08-09 15:50 UTCGHSA enrichment
  29. 2026-08-09 13:47 UTCEPSS rescore
  30. 2026-08-09 04:18 UTCEG score recompute
  31. 2026-08-09 04:18 UTCVendor advisory
  32. 2026-08-09 04:18 UTCGHSA enrichment
  33. 2026-08-08 16:37 UTCEPSS rescore
  34. 2026-08-08 01:29 UTCEG score recompute
  35. 2026-08-08 01:29 UTCVendor advisory
  36. 2026-08-08 01:29 UTCGHSA enrichment
  37. 2026-08-07 13:57 UTCEG score recompute
  38. 2026-08-07 13:57 UTCVendor advisory
  39. 2026-08-07 13:56 UTCGHSA enrichment
  40. 2026-08-06 13:47 UTCEPSS rescore
  41. 2026-08-06 12:31 UTCVendor advisory
  42. 2026-08-06 12:31 UTCGHSA enrichment
  43. 2026-08-05 23:34 UTCEG score recompute
  44. 2026-08-05 23:34 UTCVendor advisory
  45. 2026-08-05 23:34 UTCGHSA enrichment
  46. 2026-08-05 19:17 UTCEPSS rescore
  47. 2026-08-05 19:17 UTCEPSS rescore
  48. 2026-08-05 01:19 UTCEG score recompute
  49. 2026-08-05 01:19 UTCVendor advisory
  50. 2026-08-05 01:19 UTCGHSA enrichment
  51. 2026-08-05 00:51 UTCEG score recompute
  52. 2026-08-05 00:51 UTCVendor advisory
  53. 2026-08-05 00:51 UTCGHSA enrichment
  54. 2026-08-04 15:10 UTCEPSS rescore
  55. 2026-08-04 10:39 UTCEPSS rescore
  56. 2026-08-03 21:48 UTCEG score recompute
  57. 2026-08-03 21:48 UTCVendor advisory
  58. 2026-08-03 21:48 UTCGHSA enrichment
  59. 2026-08-03 10:36 UTCEPSS rescore
  60. 2026-08-03 01:09 UTCVendor advisory
  61. 2026-08-03 01:09 UTCGHSA enrichment
  62. 2026-08-02 13:33 UTCEG score recompute
  63. 2026-08-02 13:33 UTCVendor advisory
  64. 2026-08-02 13:33 UTCGHSA enrichment
  65. 2026-08-02 02:27 UTCEPSS rescore
  66. 2026-08-01 04:16 UTCEPSS rescore
  67. 2026-07-30 16:28 UTCEPSS rescore
  68. 2026-07-30 01:30 UTCEPSS rescore
  69. 2026-07-28 15:37 UTCEPSS rescore
  70. 2026-07-27 14:14 UTCEPSS rescore
  71. 2026-07-26 14:54 UTCEPSS rescore
  72. 2026-07-26 14:54 UTCEPSS rescore
  73. 2026-07-25 14:18 UTCEPSS rescore
  74. 2026-07-25 14:18 UTCEPSS rescore
  75. 2026-07-24 14:18 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-6100?
CVE-2026-6100 is a high vulnerability published on April 13, 2026. 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…
When was CVE-2026-6100 disclosed?
CVE-2026-6100 was first published in the National Vulnerability Database on April 13, 2026, with the most recent update on August 13, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-6100 actively exploited?
CVE-2026-6100 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 54.7% of all scored CVEs.
What is the CVSS score of CVE-2026-6100?
CVE-2026-6100 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2026-6100?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-6100, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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