IBM HTTP Server 8.5, and 9.0 is vulnerable to remote code execution and denial of service in configurations with TLS mutual authentication (client authentication).
CVE-2026-8855
“—” beside the score: it is equal to NVD's CVSS score.
This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 0.8% (57th percentile of EPSS-scored CVEs). GitHub Security Advisory CVSS 8.1 is lower than this score; a lower GitHub score revises it only when its advisory is newer than the CVE record's last change, and this advisory (published 2026-05-26) is not newer than that change (2026-07-23), so it does not.
- High severity, but no confirmed exploitation yet
A fix is referenced (a reference tagged "Patch", often a source commit), but no release containing it is confirmed — find the release that contains it; until it is applied, mitigate (WAF / firewall / segmentation).
- CVSS v3
- 9.8
- EG Score
- 9.8CRITICALmedium confidence
- EG Risk
- 44EG Risk 44/100
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.Exploitation0.9% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.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 none (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 referenced, but no release containing it is confirmed. Check the referenced fix and the vendor's advisory for a release that contains it and apply that within your standard update timelines; until then, restrict network exposure of the affected system or apply the vendor's mitigation. - EPSS PROB
- 0.8%
- EPSS %ILE
- 57th
- 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.NVD CVSS v3 · CVSS v3.0 or v3.1
- EG Likelihood
- 0.8% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-19). 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; Track* at high (mission-essential systems).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: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is referenced, but no release containing it is confirmed. Check the referenced fix and the vendor's advisory for a release that contains it and apply that within your standard update timelines; until then, restrict network exposure of the affected system or apply the vendor's mitigation.
Exploitation none (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.
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
May 26, 2026
Last Modified
July 23, 2026
Advisory Details (1)
Auto-updated Oct 17, 2026Security Bulletin: IBM HTTP Server is affected by multiple vulnerabilities
https://www.ibm.com/support/pages/node/7274065Vendor Advisories for CVE-2026-8855(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 / 45× 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 97 of 308 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. 3 repeat rows among the latest 100 are merged into the row they repeat. The 211 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-10-20 05:35 UTCEG score recompute
- 2026-10-20 05:35 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.8% · 57th percentile
- 2026-10-19 07:12 UTCEG score recompute
- 2026-10-19 07:11 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.8% · 57th percentile
- 2026-10-18 08:45 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-18 03:03 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.8% · 57th percentile
- 2026-10-17 10:21 UTCEG score recompute
- 2026-10-17 10:21 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.8% · 57th percentile
- 2026-10-16 11:58 UTCEG score recompute
- 2026-10-16 11:57 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.8% · 57th percentile
- 2026-10-15 13:11 UTCEG score recompute
- 2026-10-15 13:10 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-14 16:34 UTCEPSS rescoreEPSS 0.8% · 57th percentile
- 2026-10-14 08:18 UTCEG score recompute
- 2026-10-14 08:18 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.8% · 57th percentile
- 2026-10-13 03:33 UTCEG score recompute
- 2026-10-13 03:32 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-12 14:49 UTCEG score recompute
Show 72 moreShow fewer
- 2026-10-12 05:09 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-11 19:15 UTCEG score recompute
- 2026-10-11 16:32 UTCEG score recompute
- 2026-10-11 13:50 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-11 13:48 UTCEG score recompute
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-05 17:44 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-01 19:51 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-09-27 13:49 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-17 19:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-16 14:09 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-13 16:48 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-12 15:02 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-11 09:38 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-06 13:48 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-05 15:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-30 19:18 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-28 21:42 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-26 14:47 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-24 14:18 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-24 00:11 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-23 19:47 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-23 15:57 UTCEG score recompute
- 2026-08-23 15:57 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-08-22 01:13 UTCEG score recompute
- 2026-08-22 01:13 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-08-21 21:22 UTCEG score recompute
- 2026-08-21 21:22 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-20 22:56 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-08-20 22:42 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-20 18:02 UTCEG score recompute
- 2026-08-20 18:02 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-08-18 13:49 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-17 13:22 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-17 09:32 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-16 16:31 UTCEG score recompute
- 2026-08-16 16:31 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-16 10:44 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-16 06:54 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-16 03:04 UTCEG score recompute
- 2026-08-16 03:04 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-08-16 02:15 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-15 01:31 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-08-15 00:42 UTCGHSA enrichmentGHSA-rjqm-vgmr-8cp8 · GitHub severity HIGH · GitHub CVSS 8.1
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Frequently asked(5)
What is CVE-2026-8855?
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What is the CVSS score of CVE-2026-8855?
How do I remediate CVE-2026-8855?
Dependency Blast Radius
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