A use-after-free vulnerability was found in QEMU's 9pfs subsystem. A race condition between the main thread and a worker thread when processing concurrent Tlcreate and Twalk requests allows a malicious guest user to craft a fid path containing stale heap data, bypassing directory traversal restrictions and escaping the shared directory boundary. This can lead to arbitrary host file read/write and code execution (VM escape) as the QEMU process user.
CVE-2026-93834
“—” beside the score: it is equal to the CVSS score beside it.
Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2026-09-25. A secondary CVSS source baseline 8.8; sources differ by 0.0.
Also known asEUVD-2026-87092 (ENISA EUVD) · GHSA-86c2-8qp8-q2vh (GitHub Security Advisories)Source: ENISA EUVD
- Public exploit or proof-of-concept code is available
A fix is available — apply it.
- CVSS v3
- 8.8
- EG Score
- 8.8HIGHmedium confidence
- EG Risk
- 56EG Risk 56/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity88% × 45%Impact severity (EG Severity): CVSS 8.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.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, Track* at medium and Attend at high mission impact.Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 0.4%
- EPSS %ILE
- 34th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (8.8): severity, escalated by confirmed exploitation. This CVE's 8.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 8.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-30). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track* at medium mission impactTrack at low, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (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
September 25, 2026
Last Modified
October 31, 2026
Advisory Details (3)
Auto-updated Sep 25, 2026VM guest escape via 9p filesystem exploit (#4491) · Issues · QEMU / QEMU · GitLab
https://gitlab.com/qemu-project/qemu/-/work_items/44912537939 – (CVE-2026-93834) CVE-2026-93834 qemu-kvm: 9pfs: use-after-free race in Tlcreate/Twalk allows VM guest escape
https://bugzilla.redhat.com/show_bug.cgi?id=2537939CVE-2026-93834 - Red Hat Customer Portal
Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a
https://access.redhat.com/security/cve/CVE-2026-93834Vendor Advisories for CVE-2026-93834(2)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(3 across 3 ecosystems)
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| qemu | 1:10.0.0+ds-1 ... 1:9.2.2+ds-1~bpo12+1 (200 versions) |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| qemu | 1:10.0.10+ds-0+deb13u1 ... 1:11.1.2+ds-1 (67 versions) |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| qemu | 1:10.0.2+ds-2 ... 1:11.1.1+ds-1 (56 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 13× in last 7d / 94× 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.
Showing the most recent 100 of 133 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 33 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-01 16:36 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-31 08:26 UTCEG score recompute
- 2026-10-31 08:26 UTCVendor advisory
- 2026-10-31 08:26 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-31 08:04 UTCEG score recompute
- 2026-10-31 08:04 UTCVendor advisory
- 2026-10-31 08:04 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-27 16:33 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-26 16:33 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-25 15:34 UTCEG score recompute
- 2026-10-25 15:34 UTCVendor advisory
- 2026-10-25 15:34 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-25 13:49 UTCEG score recompute
- 2026-10-24 16:34 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-23 16:33 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-20 17:47 UTCEG score recompute
- 2026-10-20 17:46 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-20 16:34 UTCEPSS rescoreEPSS 0.4% · 30th percentile
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- 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-18 02:58 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-16 16:45 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.4% · 30th percentile
- 2026-10-14 16:34 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-13 04:22 UTCEG score recompute
- 2026-10-13 04:22 UTCVendor advisory
- 2026-10-13 04:22 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-12 14:42 UTCEG score recompute
- 2026-10-12 02:08 UTCVendor advisory
- 2026-10-12 02:07 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-11 19:12 UTCEG score recompute
- 2026-10-11 16:28 UTCEG score recompute
- 2026-10-11 14:32 UTCEG score recompute
- 2026-10-11 14:32 UTCVendor advisory
- 2026-10-11 14:32 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-11 13:50 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-11 13:41 UTCEG score recompute
- 2026-10-11 02:57 UTCEG score recompute
- 2026-10-11 02:57 UTCVendor advisory
- 2026-10-11 02:56 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-10 15:17 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-10 03:42 UTCEG score recompute
- 2026-10-10 03:42 UTCVendor advisory
- 2026-10-10 03:42 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-09 20:08 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-09 16:07 UTCVendor advisory
- 2026-10-09 16:06 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-09 04:32 UTCEG score recompute
- 2026-10-09 04:32 UTCVendor advisory
- 2026-10-09 04:32 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-08 17:14 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-08 16:57 UTCVendor advisory
- 2026-10-08 16:57 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-08 05:16 UTCEG score recompute
- 2026-10-08 05:16 UTCVendor advisory
- 2026-10-08 05:16 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-07 17:40 UTCVendor advisory
- 2026-10-07 17:40 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-07 04:23 UTCVendor advisory
- 2026-10-07 04:23 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-06 16:48 UTCEG score recompute
- 2026-10-06 16:48 UTCVendor advisory
- 2026-10-06 16:48 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-06 15:19 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-06 05:12 UTCEG score recompute
- 2026-10-06 05:12 UTCVendor advisory
- 2026-10-06 05:12 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-05 17:44 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-05 17:30 UTCVendor advisory
- 2026-10-05 17:30 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-05 05:54 UTCEG score recompute
- 2026-10-05 05:54 UTCVendor advisory
- 2026-10-05 05:54 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-04 23:23 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-04 18:16 UTCVendor advisory
- 2026-10-04 18:16 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-04 06:41 UTCVendor advisory
- 2026-10-04 06:41 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-03 19:07 UTCEG score recompute
- 2026-10-03 19:07 UTCVendor advisory
- 2026-10-03 19:07 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-03 07:32 UTCVendor advisory
- 2026-10-03 07:31 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-02 19:54 UTCEG score recompute
- 2026-10-02 19:54 UTCVendor advisory
- 2026-10-02 19:54 UTCGHSA enrichmentGHSA-86c2-8qp8-q2vh · GitHub severity HIGH · GitHub CVSS 8.8
- 2026-10-02 08:19 UTCVendor advisory
Publicly available exploits
(1 reference)Public exploit code is referenced for this CVE (1 GitHub PoC). Defenders should treat patch urgency accordingly.
- GitHub PoCsuominen/CVE-2026-93834Published Sep 26, 2026
Tracking the QEMU CVE-2026-93834 9pfs fid-path use-after-free guest-to-host escape
Open source ↗
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Frequently asked(5)
What is CVE-2026-93834?
When was CVE-2026-93834 made public?
Is CVE-2026-93834 actively exploited?
What is the CVSS score of CVE-2026-93834?
How do I remediate CVE-2026-93834?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-93834
Is Your Infrastructure Affected by CVE-2026-93834?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.