CVE Intelligence
Low Logic error

CVE-2026-1035 — Org.keycloak.protocol.oidc: keycloak refresh token reuse bypass via toctou race condition

A flaw was found in the Keycloak server during refresh token processing, specifically in the TokenManager class responsible for enforcing refresh token reuse policies. When strict refresh token rotation is enabled, the validation and update of refresh token usage are not performed atomically. This allows concurrent refresh requests to bypass single-use enforcement and issue multiple access tokens from the same refresh token. As a result, Keycloak’s refresh token rotation hardening can be undermined.

Published Jan 21, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: redhat

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.3% (30-day exploitation probability)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.31%
ahead of 22% of scored CVEs · Oct 14, 2026
Affects
Red Hat
Red Hat build of Keycloak 26.4
CVSS base
3.1
Low · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Red Hat Red Hat build of Keycloak 26.4).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes matching the vulnerability class (logic error), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Red Hat Red Hat build of Keycloak 26.4 versions not specified by the source Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
3.1 CVSS 3.1 Low 1.6 1.4 secalert@redhat.com via NIST National Vulnerability Database
3.1 CVSS 3.1 Low — — redhat via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N (score shown at the top: secalert@redhat.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-367 · TOCTOU Race Condition

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.31%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · red hat/red hat build of keycloak 26.4
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • CVSS changed · 3.1
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Deferred
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVE published
    Jan 21, 2026 · redhat

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

4 on the record

Elsewhere on this site

Red Hat
every CVE for this vendor
Logic error
same class
CWE-367
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-4629 Keycloak: keycloak: privilege escalation through hardcoded role mapper injection Jun 30, 2026
  • CVE-2026-14209 Keycloak-admin-ui: keycloak-admin-ui:admin ui extension brute-force-user endpoint bypasses fgapv2 user view restrictions Jun 30, 2026
  • CVE-2026-9800 Keycloak-policy-enforcer: keycloak policy enforcer: authorization bypass via incorrect uri comparison Jun 25, 2026
  • CVE-2026-9799 Keycloak: keycloak: unauthorized access to resources via uma permission ticket bypass Jun 25, 2026
  • CVE-2026-9705 Keycloak: keycloak: attacker can re-enable and take over disabled clients via registration access token Jun 25, 2026
  • CVE-2026-9083 Keycloak: keycloak: information disclosure through arbitrary filesystem path probing Jun 25, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-1035 is "Org.keycloak.protocol.oidc: keycloak refresh token reuse bypass via toctou race condition", rated Low. It affects Red Hat build of Keycloak 26.4 (Red Hat); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 3.1 describes technical severity. EPSS 0.31% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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