SumatraPDF is a multi-format reader for Windows. In 3.6.1 and earlier, and in pre-release 3.7.0.20369 when WebView2 is absent or cannot initialize, ParseProtoUrl() accepts the signed host component of an its:// URL and FindHtmlWindowById() uses it directly as an index into gHtmlWindows. Opening a crafted CHM through the IE fallback backend with a negative or otherwise out-of-range window identifier can cause an out-of-bounds pointer read followed by an invalid object callback dereference and process termination. No fixed version is available as of this review.
CVE-2026-107737
MEDIUMPre-NVD 5.75.7Trending — 3 sources updated this weekElevatedEG-KEV Tier 3: ElevatedEG-KEV is EchelonGraph's own tiering of exploitation signals from CISA KEV, CISA's SSVC data (Vulnrichment), ransomware data, public exploit-code references and EPSS.Tier 3 is not evidence of exploitation. It means public exploit code is referenced, or CISA's SSVC data says "public PoC", or EPSS ranks the CVE in the top 5%.Signals for this CVE: CISA's SSVC exploitation value: public PoC.EchelonGraph confidence 38%: a heuristic from the tier and the number of signals, not a measured probability.
EchelonGraph scoreMEDIUM confidence
“—” beside the score: it is equal to the CVSS score beside it.
This medium-severity CVE scores 5.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1% (1st percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
5.7EG
EchelonGraph verdictPlan mitigationRemediate within your standard update timelines (the SSVC decision on this page).
- CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 5.7Exploit: No code on recordExposed services: Not assessed
No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.
- CVSS v3
- 5.7
- EG Score
- 5.7MEDIUMmedium confidence
- EG Risk
- 42EG Risk 42/100
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 (value × EchelonGraph’s weight)Severity57% × 45%The EG Score, 5.7 of 10.Exploitation40% × 40%EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: No fix is confirmed yet. Restrict network exposure of the affected system within your standard update timelines, and watch for a fix. - EPSS PROB
- 0.1%
- EPSS %ILE
- 1st
- KEV
- Not listed
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
No fix is confirmed yet. Restrict network exposure of the affected system within your standard update timelines, and watch for a fix.
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
October 8, 2026
Last Modified
October 13, 2026
Advisory Details (2)
Auto-updated Oct 8, 2026No fix on record yet. Sources: github, github_commit.
GitHub commit
commit 596c7e26e983 (sumatrapdfreader/sumatrapdf)
Fix landed in sumatrapdfreader/sumatrapdf commit 596c7e26e983 — awaiting tagged release
https://github.com/sumatrapdfreader/sumatrapdf/commit/596c7e26e983549a77a3a38cae1147ab73792929GitHub advisoryMentions a patch (unverified)
SumatraPDF CHM `its://` signed index causes an out-of-bounds object lookup · Advisory · sumatrapdfreader/sumatrapdf · GitHub
https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-8p34-f32f-7rmqWeakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 16× in last 7d / 16× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
- 2026-10-13 17:28 UTCEG score recompute
- 2026-10-13 16:40 UTCEG score recompute
- 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-12 16:38 UTCEG score recompute
- 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-11 20:14 UTCEG score recompute
- 2026-10-11 18:26 UTCEG score recompute
- 2026-10-11 15:00 UTCEG score recompute
- 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-10 23:22 UTCEG score recompute
- 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-09 23:22 UTCEG score recompute
- 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-10-08 23:22 UTCEG score recompute
- 2026-10-08 22:38 UTCEG score recomputeFirst assessed: 5.7 MEDIUM
- 2026-10-08 22:38 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-107737?
CVE-2026-107737 is a medium-severity vulnerability; its CVE record was published on October 8, 2026. SumatraPDF is a multi-format reader for Windows. In 3.6.1 and earlier, and in pre-release 3.7.0.20369 when WebView2 is absent or cannot initialize, ParseProtoUrl() accepts the signed host component of an its:// URL and FindHtmlWindowById() uses it directly as an index into gHtmlWindows. Opening a…
When was the CVE record for CVE-2026-107737 published?
The CVE record for CVE-2026-107737 was published on October 8, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 13, 2026; the record at its source may have been updated since.
Is CVE-2026-107737 actively exploited?
CVE-2026-107737 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (1st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-107737?
CVE-2026-107737 has a CVSS base score of 5.7 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-107737?
No fix for CVE-2026-107737 is confirmed yet. Until one is published, restrict network exposure of the affected system — for example, keep it off the internet or limit it to trusted networks — and watch for a fix.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-107737
Is Your Infrastructure Affected by CVE-2026-107737?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.