Hermes WebUI before version 0.51.270 contains a resource exhaustion vulnerability that allows unauthenticated remote attackers to degrade service availability by repeatedly calling the passkey options endpoint without completing assertion. Attackers can send unlimited POST requests to the authentication endpoint, causing unbounded growth of the challenge store file and excessive CPU and disk I/O through repeated JSON file rewrites.
CVE-2026-49955
“—” beside the score: it is equal to the CVSS score beside it.
Score 5.3 from GitHub Security Advisory published 2026-06-09. A secondary CVSS source baseline 5.3; sources differ by 0.0.
Also known asEUVD-2026-35494 (ENISA EUVD) · GHSA-wwx5-jq7h-rp7v (GitHub Security Advisories)Source: ENISA EUVD
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 5.3
- EG Score
- 5.3MEDIUMmedium confidence
- EG Risk
- 39EG Risk 39/100
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)Severity53% × 45%Impact severity (EG Severity): CVSS 5.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.8% × 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 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: 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
- 0.6%
- EPSS %ILE
- 48th
- 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 (5.3): severity, escalated by confirmed exploitation. This CVE's 5.3 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.3 MEDIUMCVSS-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. 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: 14 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).
A fix is available. 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 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)14 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 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
June 9, 2026
Last Modified
July 23, 2026
Advisory Details (5)
Auto-updated Jun 16, 2026Hermes WebUI < 0.51.270 Resource Exhaustion via passkey/options | Advisories | VulnCheck
https://www.vulncheck.com/advisories/hermes-webui-resource-exhaustion-via-passkey-optionsv0.51.270
Patch available: nesquena/hermes-webui v0.51.270
https://github.com/nesquena/hermes-webui/releases/tag/v0.51.270Release v0.51.270 — Release IL (stage-u1 — un-hold batch: #3517 #3624 #3613)
Patch available: nesquena/hermes-webui v0.51.424 (PR #3674 merged 2026-06-05)
https://github.com/nesquena/hermes-webui/pull/3674[security] fix(auth): cap pending passkey challenges
Upstream fix in progress (PR #3624 · nesquena/hermes-webui, state=closed)
https://github.com/nesquena/hermes-webui/pull/3624commit 58528a4d88b0 (nesquena/hermes-webui)
Patch available: nesquena/hermes-webui v0.51.424 (contains commit 58528a4d88b0)
https://github.com/nesquena/hermes-webui/commit/58528a4d88b0fa4f7b822e31d6051c669769bd3bVendor Advisories for CVE-2026-49955(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 8× in last 7d / 39× 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 233 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 133 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-30 13:25 UTCOSV refresh
- 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-25 14:22 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-22 22:59 UTCEG score recompute
- 2026-10-22 22:59 UTCGHSA enrichmentGHSA-wwx5-jq7h-rp7v · GitHub CVSS 5.3
- 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-18 03:33 UTCEG score recompute
- 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.8% · 55th percentile
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- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-12 15:59 UTCEG score recompute
- 2026-10-11 19:42 UTCEG score recompute
- 2026-10-11 16:57 UTCEG score recompute
- 2026-10-11 14:21 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-03 09:39 UTCOSV refresh
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-26 00:27 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-09-14 04:35 UTCEG score recompute
- 2026-09-14 04:35 UTCGHSA enrichmentGHSA-wwx5-jq7h-rp7v · GitHub CVSS 5.3
- 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-31 00:55 UTCEG score recompute
- 2026-08-31 00:55 UTCGHSA enrichmentGHSA-wwx5-jq7h-rp7v · GitHub CVSS 5.3
- 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-25 00:50 UTCEG score recompute
- 2026-08-25 00:50 UTCGHSA enrichmentGHSA-wwx5-jq7h-rp7v · GitHub CVSS 5.3
- 2026-08-23 11:13 UTCEG score recompute
- 2026-08-23 11:13 UTCGHSA enrichmentGHSA-wwx5-jq7h-rp7v · GitHub CVSS 5.3
- 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-21 12:24 UTCEG score recompute
- 2026-08-21 12:24 UTCGHSA enrichmentGHSA-wwx5-jq7h-rp7v · GitHub CVSS 5.3
- 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-20 09:07 UTCEG score recompute
- 2026-08-20 09:07 UTCGHSA enrichmentGHSA-wwx5-jq7h-rp7v · GitHub CVSS 5.3
- 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-17 04:36 UTCEG score recompute
- 2026-08-17 04:36 UTCGHSA enrichmentGHSA-wwx5-jq7h-rp7v · GitHub CVSS 5.3
- 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-16 02:30 UTCEG score recompute
- 2026-08-16 02:30 UTCGHSA enrichmentGHSA-wwx5-jq7h-rp7v · GitHub CVSS 5.3
- 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-15 00:26 UTCGHSA enrichmentGHSA-wwx5-jq7h-rp7v · GitHub CVSS 5.3
- 2026-08-13 22:21 UTCEG score recompute
- 2026-08-13 22:21 UTCGHSA enrichmentGHSA-wwx5-jq7h-rp7v · GitHub CVSS 5.3
- 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-08-12 13:36 UTCEG score recompute
- 2026-08-12 13:36 UTCGHSA enrichmentGHSA-wwx5-jq7h-rp7v · GitHub CVSS 5.3
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Frequently asked(5)
What is CVE-2026-49955?
When was CVE-2026-49955 made public?
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What is the CVSS score of CVE-2026-49955?
How do I remediate CVE-2026-49955?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-49955
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