CVE-2026-84309

MEDIUMPre-NVD 6.96.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 97% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
6.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.9Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

pypdf is a free and open-source pure-python PDF library. Prior to 6.16.0, an attacker can craft a PDF whose cyclic tree structure causes pypdf/generic/_data_structures.py TreeObject.insert_child to follow /Next links indefinitely when a writing code path inserts a child, producing an infinite loop. This issue is fixed in version 6.16.0.

CVSS v3
6.9
EG Score
6.9(medium)
EG Risk
31(Track)
EG Risk 31/100SSVC: 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
Severity69% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
3%
KEV
Not listed

Published

September 1, 2026

Last Modified

September 9, 2026

Advisory Details (4)

Auto-updated Sep 1, 2026
Patch available. Sources: github_commit, github_pr, github_release, github.
github Patch Available

Possible infinite loop for TreeObject.insert_child · Advisory · py-pdf/pypdf · GitHub

https://github.com/py-pdf/pypdf/security/advisories/GHSA-jp53-mhqp-8xcg
github_release Patch Available

Version 6.16.0, 2026-08-13

Patch available: py-pdf/pypdf 6.16.0

https://github.com/py-pdf/pypdf/releases/tag/6.16.0
github_pr Patch Available

SEC: Detect cycles in TreeObject.insert_child

Patch available: py-pdf/pypdf 6.16.0 (PR #3964 merged 2026-08-13)

https://github.com/py-pdf/pypdf/pull/3964
github_commit Patch Available

commit c9ba557d565d (py-pdf/pypdf)

Patch available: py-pdf/pypdf 6.16.0 (contains commit c9ba557d565d)

https://github.com/py-pdf/pypdf/commit/c9ba557d565d57c53a0b3a0be06c0a4c29b0559b

Vendor Advisories for CVE-2026-84309(1)

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

Affected Packages

(5 across 4 ecosystems)
Debian:12(2)
PackageVulnerable rangeFixed inDependents
pypdf3.17.4-1 ... 6.9.2-2 (14 versions)——
pypdf22.12.1-3, 2.12.1-3+deb12u1, 2.12.1-4——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
pypdf5.4.0-1, 6.9.0-1, 6.9.2-1, 6.9.2-2——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
pypdf5.4.0-1, 6.9.0-1, 6.9.2-1, 6.9.2-2——
PyPI(1)
PackageVulnerable rangeFixed inDependents
pypdf1.0 ... 6.9.2 (113 versions)6.16.0—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 29× 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.

  1. 2026-09-18 21:25 UTCEG score recompute
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-17 20:41 UTCEG score recompute
  4. 2026-09-17 19:32 UTCEPSS rescore
  5. 2026-09-16 18:54 UTCEG score recompute
  6. 2026-09-16 14:09 UTCEPSS rescore
  7. 2026-09-16 05:15 UTCEPSS rescore
  8. 2026-09-15 18:42 UTCEG score recompute
  9. 2026-09-15 03:12 UTCEPSS rescore
  10. 2026-09-15 03:12 UTCEPSS rescore
  11. 2026-09-13 17:43 UTCEG score recompute
  12. 2026-09-12 17:35 UTCEG score recompute
  13. 2026-09-11 17:27 UTCEG score recompute
  14. 2026-09-11 14:53 UTCEPSS rescore
  15. 2026-09-11 14:53 UTCEPSS rescore
  16. 2026-09-10 17:02 UTCEG score recompute
  17. 2026-09-08 23:20 UTCEG score recompute
  18. 2026-09-08 22:01 UTCEPSS rescore
  19. 2026-09-06 15:07 UTCEG score recompute
  20. 2026-09-06 13:48 UTCEPSS rescore
  21. 2026-09-05 15:31 UTCEPSS rescore
  22. 2026-09-04 14:49 UTCEG score recompute
  23. 2026-09-04 05:07 UTCEPSS rescore
  24. 2026-09-02 14:31 UTCEG score recompute
  25. 2026-09-02 14:12 UTCEPSS rescore
Show 4 more
  1. 2026-09-02 13:52 UTCEG score recompute
  2. 2026-09-01 20:18 UTCEG score recompute
  3. 2026-09-01 20:03 UTCEG score recompute
  4. 2026-09-01 20:02 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-84309?
CVE-2026-84309 is a medium vulnerability published on September 1, 2026. pypdf is a free and open-source pure-python PDF library. Prior to 6.16.0, an attacker can craft a PDF whose cyclic tree structure causes pypdf/generic/datastructures.py TreeObject.insert_child to follow /Next links indefinitely when a writing code path inserts a child, producing an infinite loop.…
When was CVE-2026-84309 disclosed?
CVE-2026-84309 was first published in the National Vulnerability Database on September 1, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-84309 actively exploited?
CVE-2026-84309 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 97.3% of all scored CVEs.
What is the CVSS score of CVE-2026-84309?
CVE-2026-84309 has a CVSS v3 base score of 6.9 (NVD).
How do I remediate CVE-2026-84309?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-84309, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-84309

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