CVE-2026-104721

MEDIUMPre-NVD 6.36.3
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This medium-severity CVE scores 6.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (26th 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
Trending — 3 sources updated this week

Also known asEUVD-2026-91633 (ENISA EUVD) · GHSA-5f86-rhcp-cxm6 (GitHub Security Advisories)Source: ENISA EUVD

6.3EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 6.3Exploit: None knownExposed services: Not assessed

Update to logack version 1.6.5 or later (from the CVE record's solution, Switzerland National Cyber Security Centre (NCSC)) — apply it.

Path-traversal vulnerability in QOS.CH Sarl Logback-classic on Java (logback-classic module) allows path-traversal vulnerability. More specifically, an MDC-based discriminator value flows unsanitized into a nested FileAppender path, letting an attacker who influences that MDC value (e.g. via an HTTP header) create and append log files outside the intended directory.

This issue affects Logback-classic: from 0.9.14 through 1.6.4.  This vulnerability is similar to CVE-2026-19880 but involves other attack techniques.

CVSS v3
6.3
EG Score
6.3MEDIUMmedium confidence
EG Risk
28
EG Risk 28/100

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)
Severity63% × 45%
Impact severity (EG Severity): CVSS 6.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.3% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
The CVE's CVSS v4.0 Automatable metric (AU): no. CERT/CC intends it to be interchangeable with SSVC's Automatable.
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CVSS v4.0 Automatable metric) · Technical impact partial (CVSS v4.0 confidentiality and integrity impact neither High). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: Update to logack version 1.6.5 or later (from the CVE record's solution, Switzerland National Cyber Security Centre (NCSC)). Apply it within your standard update timelines.
EPSS PROB
0.3%
EPSS %ILE
26th
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 (6.3): severity, escalated by confirmed exploitation. This CVE's 6.3 is its impact severity (EG Severity), not escalated.

EG Severity
6.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-28). 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 every mission impact level.CISA BOD 26-04: 60 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 every mission impact level.

Update to logack version 1.6.5 or later (from the CVE record's solution, Switzerland National Cyber Security Centre (NCSC)). Apply it within your standard update timelines.

Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CVSS v4.0 Automatable metric) · Technical impact partial (CVSS v4.0 confidentiality and integrity impact neither High). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from 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.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CVSS v4.0 Automatable metric) · Technical impact partial (CVSS v4.0 confidentiality and integrity impact neither High). 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 2, 2026

Last Modified

October 2, 2026

Advisory Details (1)

Auto-updated Oct 2, 2026
Fix named in the CVE record's solution (Switzerland National Cyber Security Centre (NCSC)).

Vendor Advisories for CVE-2026-104721(1)

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)
PackageVulnerable rangeFix by version rangeDependents
logback1:1.2.11-3 ... 1:1.6.3-2 (6 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
logback1:1.2.11-6, 1:1.6.3-1, 1:1.6.3-2
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
logback1:1.2.11-6, 1:1.6.3-1, 1:1.6.3-2
  • every version on: no fix on record
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 52× 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.

  1. 2026-11-02 16:43 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  2. 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  3. 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  4. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  5. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  6. 2026-10-29 14:52 UTCEG score recompute
  7. 2026-10-29 14:52 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  8. 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  9. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  10. 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  11. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  12. 2026-10-25 14:55 UTCEG score recompute
  13. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  14. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  15. 2026-10-23 09:16 UTCEG score recompute
  16. 2026-10-23 09:16 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  17. 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  18. 2026-10-21 16:31 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  19. 2026-10-20 16:31 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  20. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  21. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  22. 2026-10-18 05:09 UTCEG score recompute
  23. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  24. 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  25. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.3% · 24th percentile
Show 35 more
  1. 2026-10-14 16:31 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  2. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  3. 2026-10-12 16:40 UTCEG score recompute
  4. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  5. 2026-10-11 20:14 UTCEG score recompute
  6. 2026-10-11 20:14 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  7. 2026-10-11 18:27 UTCEG score recompute
  8. 2026-10-11 15:01 UTCEG score recompute
  9. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  10. 2026-10-10 20:01 UTCEG score recompute
  11. 2026-10-10 20:01 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  12. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  13. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  14. 2026-10-09 19:52 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  15. 2026-10-08 19:43 UTCEG score recompute
  16. 2026-10-08 19:43 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  17. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  18. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  19. 2026-10-07 19:03 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  20. 2026-10-06 18:54 UTCEG score recompute
  21. 2026-10-06 18:54 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  22. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  23. 2026-10-05 18:46 UTCEG score recompute
  24. 2026-10-05 18:46 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  25. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  26. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  27. 2026-10-04 18:36 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  28. 2026-10-03 18:26 UTCEG score recompute
  29. 2026-10-03 18:25 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  30. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  31. 2026-10-02 18:15 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  32. 2026-10-02 18:14 UTCGHSA enrichmentGHSA-5f86-rhcp-cxm6
  33. 2026-10-02 14:22 UTCEG score recompute
  34. 2026-10-02 13:26 UTCEG score recomputeFirst assessed: 6.3 MEDIUM
  35. 2026-10-02 13:25 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-104721?
CVE-2026-104721 is a medium-severity vulnerability; its CVE record was published on October 2, 2026. Path-traversal vulnerability in QOS.CH Sarl Logback-classic on Java (logback-classic module) allows path-traversal vulnerability. More specifically, an MDC-based discriminator value flows unsanitized into a nested FileAppender path, letting an attacker who influences that MDC value (e.g. via an…
When was CVE-2026-104721 made public?
CVE-2026-104721 was made public on August 14, 2026: that is the date its CVE record's CNA, Switzerland National Cyber Security Centre (NCSC), gives for when the vulnerability was made public. The CVE record itself was published on October 2, 2026. EchelonGraph's copy of the record carries a last-modified date of October 2, 2026; the record at its source may have been updated since.
Is CVE-2026-104721 actively exploited?
CVE-2026-104721 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (26th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-104721?
CVE-2026-104721 has a CVSS base score of 6.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-104721?
The CVE record's solution for CVE-2026-104721, written by its CNA Switzerland National Cyber Security Centre (NCSC), names the fix: "Update to logack version 1.6.5 or later." The vendor advisories EchelonGraph has for CVE-2026-104721 are linked in the Vendor Advisories panel on this page.

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