CVE-2026-77220

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreHIGH confidence

Score 6.5 from GitHub Security Advisory (severity: HIGH) published 2026-08-21. a secondary CVSS source baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: None knownExposed: 0

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

PDFio before 1.6.5 contains a dangling pointer vulnerability in the dictionary string-formatting function that stores a pointer to a stack-local buffer in the document dictionary without copying the string value. In multi-threaded or pooled-request environments, attackers or concurrent users can trigger stack memory reuse across requests, causing cross-tenant document content corruption by silently overwriting one caller's dictionary string values with another caller's data.

CVSS v3
6.5
EG Score
6.5(high)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
15%
KEV
Not listed

Published

August 21, 2026

Last Modified

August 24, 2026

Advisory Details (3)

Auto-updated Aug 21, 2026
Patch available. Sources: github_commit, github_release.
generic

PDFio < 1.6.5 Dangling Pointer via Dictionary String-Formatting | Advisories | VulnCheck

https://www.vulncheck.com/advisories/pdfio-dangling-pointer-via-dictionary-string-formatting
github_release Patch Available

Release v1.6.5 (michaelrsweet/pdfio)

Patch available: michaelrsweet/pdfio v1.6.5

https://github.com/michaelrsweet/pdfio/releases/tag/v1.6.5
github_commit Patch Available

commit 22b9afc800c5 (michaelrsweet/pdfio)

Patch available: michaelrsweet/pdfio v1.6.5 (contains commit 22b9afc800c5)

https://github.com/michaelrsweet/pdfio/commit/22b9afc800c5833f9e851e35938972bd4c76a357

Vendor Advisories for CVE-2026-77220(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 18× in last 7d / 18× 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. 2026-08-25 18:53 UTCEG score recompute
  2. 2026-08-25 18:53 UTCGHSA enrichment
  3. 2026-08-25 13:49 UTCEPSS rescore
  4. 2026-08-24 20:27 UTCEG score recompute
  5. 2026-08-24 20:27 UTCGHSA enrichment
  6. 2026-08-24 19:51 UTCEG score recompute
  7. 2026-08-24 19:51 UTCGHSA enrichment
  8. 2026-08-24 16:56 UTCEG score recompute
  9. 2026-08-24 16:56 UTCGHSA enrichment
  10. 2026-08-24 14:18 UTCEPSS rescore
  11. 2026-08-23 18:13 UTCEG score recompute
  12. 2026-08-23 18:13 UTCGHSA enrichment
  13. 2026-08-23 00:19 UTCEPSS rescore
  14. 2026-08-22 19:49 UTCEG score recompute
  15. 2026-08-22 19:49 UTCGHSA enrichment
  16. 2026-08-21 21:24 UTCEG score recompute
  17. 2026-08-21 21:05 UTCEG score recompute
  18. 2026-08-21 21:04 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-77220?
CVE-2026-77220 is a medium vulnerability published on August 21, 2026. PDFio before 1.6.5 contains a dangling pointer vulnerability in the dictionary string-formatting function that stores a pointer to a stack-local buffer in the document dictionary without copying the string value. In multi-threaded or pooled-request environments, attackers or concurrent users can…
When was CVE-2026-77220 disclosed?
CVE-2026-77220 was first published in the National Vulnerability Database on August 21, 2026, with the most recent update on August 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-77220 actively exploited?
CVE-2026-77220 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 85.2% of all scored CVEs.
What is the CVSS score of CVE-2026-77220?
CVE-2026-77220 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-77220?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-77220, 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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