Traefik is a HTTP reverse proxy and load balancer. In versions >= v3.7.0 and <= v3.7.11, the Kubernetes ingress-nginx provider mishandles Ingresses that carry both an authentication annotation and the nginx.ingress.kubernetes.io/from-to-www-redirect annotation. For such Ingresses the provider creates an additional 'sibling' router that matches on the host alone, carries only the RedirectRegex middleware, and still points at the parent router's protected backend service. Because RedirectRegex is not a terminal handler, a request its pattern does not match is forwarded to the backend, and because the redirect pattern only accepts a numeric port while Traefik's host matcher canonicalizes the authority via net.SplitHostPort, a request with a non-numeric or empty port (for example 'Host: www.example.com:x') selects the sibling router, misses the redirect, and is proxied to the protected backend with none of the Ingress's annotation-derived middlewares applied. This discards not only authentication (e.g. BasicAuth) but every annotation-derived middleware, including source-IP allowlisting. Traefik v2 and v3 releases before v3.7.0 are not affected. The issue is fixed in v3.7.12.
CVE-2026-88877
“—” beside the score: it is equal to the CVSS score beside it.
Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-09-10. A secondary CVSS source baseline 9.8; sources differ by 0.0.
Also known asEUVD-2026-75427 (ENISA EUVD) · GHSA-9rch-gvf7-hrfc (GitHub Security Advisories)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
The CVE record names the fixed release — apply it.
- CVSS v3
- 9.8
- EG Score
- 9.8CRITICALmedium confidence
- EG Risk
- 59EG Risk 59/100
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)Severity98% × 45%Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.7% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability100% × 15%CISA's SSVC Automatable value: yes (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).Exploitation none (CISA Vulnrichment) · Automatable yes (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: The CVE record names the fixed release. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 0.6%
- EPSS %ILE
- 51st
- 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 (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). 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 or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days 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 or medium mission impact; Attend at high (mission-essential systems).
The CVE record names the fixed release. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (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)3 days if the affected system is publicly exposed; 60 days if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (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 10, 2026
Last Modified
October 8, 2026
Advisory Details (2)
Auto-updated Oct 30, 2026Traefik v3.7.0 Authentication Bypass via from-to-www-redirect | Advisories | VulnCheck
https://www.vulncheck.com/advisories/traefik-3.7.0-authentication-bypass-via-from-to-www-redirectingress-nginx from-to-www-redirect sibling router serves the auth-protected backend without auth · Advisory · traefik/traefik · GitHub
https://github.com/traefik/traefik/security/advisories/GHSA-cjr6-pf59-jq29Vendor Advisories for CVE-2026-88877(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 21× in last 7d / 130× 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 313 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 213 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.6% · 51st percentile
- 2026-11-02 12:01 UTCEG score recompute
- 2026-11-02 12:01 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.6% · 51st percentile
- 2026-11-01 11:51 UTCEG score recompute
- 2026-11-01 11:51 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.6% · 51st percentile
- 2026-10-31 11:40 UTCEG score recompute
- 2026-10-31 11:40 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.6% · 51st percentile
- 2026-10-30 11:29 UTCEG score recompute
- 2026-10-30 11:29 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.6% · 51st percentile
- 2026-10-29 11:18 UTCEG score recompute
- 2026-10-29 11:18 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-28 11:06 UTCEG score recompute
- 2026-10-28 11:06 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-27 10:09 UTCEG score recompute
- 2026-10-27 10:09 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-26 09:57 UTCEG score recompute
- 2026-10-26 09:57 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.6% · 50th percentile
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- 2026-10-25 13:53 UTCEG score recompute
- 2026-10-25 09:47 UTCEG score recompute
- 2026-10-25 09:47 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-24 16:34 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-24 09:36 UTCEG score recompute
- 2026-10-24 09:36 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-23 09:25 UTCEG score recompute
- 2026-10-23 09:25 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-22 09:13 UTCEG score recompute
- 2026-10-22 09:13 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-21 09:01 UTCEG score recompute
- 2026-10-21 09:01 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-20 08:51 UTCEG score recompute
- 2026-10-20 08:51 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-19 08:38 UTCEG score recompute
- 2026-10-19 08:37 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-18 08:25 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-18 03:03 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-17 07:12 UTCEG score recompute
- 2026-10-17 07:11 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-16 07:01 UTCEG score recompute
- 2026-10-16 07:01 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.6% · 50th percentile
- 2026-10-15 05:48 UTCEG score recompute
- 2026-10-15 05:48 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-14 16:34 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-14 01:25 UTCEG score recompute
- 2026-10-14 01:24 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-12 21:37 UTCEG score recompute
- 2026-10-12 21:37 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-12 14:49 UTCEG score recompute
- 2026-10-11 21:51 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-11 19:15 UTCEG score recompute
- 2026-10-11 16:32 UTCEG score recompute
- 2026-10-11 15:43 UTCEG score recompute
- 2026-10-11 15:43 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-11 13:48 UTCEG score recompute
- 2026-10-11 11:46 UTCEG score recompute
- 2026-10-11 11:46 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-11 07:10 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-10 20:18 UTCEG score recompute
- 2026-10-10 20:18 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-10 16:21 UTCEG score recompute
- 2026-10-10 16:21 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-10 12:10 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-10 08:12 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-10 03:53 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-09 23:55 UTCEG score recompute
- 2026-10-09 23:55 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-09 19:56 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-09 07:45 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-09 03:48 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-08 23:50 UTCEG score recompute
- 2026-10-08 23:50 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-08 16:34 UTCEG score recompute
- 2026-10-08 16:33 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-08 16:02 UTCEG score recompute
- 2026-10-08 16:02 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-08 07:49 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-08 03:51 UTCGHSA enrichmentGHSA-9rch-gvf7-hrfc · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-07 23:53 UTCEG score recompute
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Frequently asked(5)
What is CVE-2026-88877?
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