CVE-2025-8556 — Github.com/cloudflare/circl: circl-fourq: missing and wrong validation can lead to incorrect results

Triage

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

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.

Remediation

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

• Go Github.com/cloudflare/circl: fixed in version 1.6.1 — github.com (GitHub Security Advisories)

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 Builds for Red Hat OpenShift, Red Hat Custom Metric Autoscaler operator for Red Hat Openshift, Red Hat Multicluster Global Hub…).
2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
3. Apply the fixed version or the patch documented under Remediation.
4. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Attack characteristics

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

Every base score collected

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

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-1287

Other CVEs with this weakness →

EPSS over time FIRST

Oct 26, 2026 → Oct 27, 2026 · 2 reading(s) · max 0.53%

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).

Timeline

What happened to this CVE, newest first.

• 2026
• Fix documented
  Oct 27, 2026 · GitHub Security Advisories
• Affected products added · go/github.com/cloudflare/circl
  Oct 27, 2026 · GitHub Security Advisories
• Affected products added · red hat/builds for red hat openshift, red hat/custom metric autoscaler operator for red hat openshift, red hat/multiclus
  Oct 27, 2026 · CVE Program (cve.org) e CISA ADP
• SSVC assessment updated
  Oct 27, 2026 · CVE Program (cve.org) e CISA ADP
• Record published
  Oct 27, 2026
• CVSS changed · 3.7
  Oct 27, 2026 · NIST National Vulnerability Database
• Source status changed · → Deferred
  Oct 27, 2026 · NIST National Vulnerability Database
• Record created in this database
  Oct 27, 2026 · Alertas do Telegram
• 2025
• CVE published
  Aug 6, 2025 · redhat

Source activity

Repeated readings are counted rather than listed.

• 2× References added · Oct 27, 2026 – Oct 27, 2026
• 1× Official description updated · Oct 27, 2026 – Oct 27, 2026

References

9 on the record

• nvd.nist.gov/vuln/detail/CVE-2025-8556
  GitHub Security Advisories
• github.com/advisories/GHSA-2x5j-vhc8-9cwm
  GitHub Security Advisories
• bugzilla.redhat.com/show_bug.cgi
  issue-tracking, x_refsource_REDHAT, NIST National Vulnerability Database
• access.redhat.com/security/cve/CVE-2025-8556
  vdb-entry, x_refsource_REDHAT, NIST National Vulnerability Database
• github.com/cloudflare/circl/security/advisories/GHSA-2x5j-vhc8-9cwm
  NIST National Vulnerability Database
• github.com/cloudflare/circl/tree/v1.6.1
  NIST National Vulnerability Database
• news.ycombinator.com/item
  NIST National Vulnerability Database
• github.com/cloudflare/circl
  NIST National Vulnerability Database
• www.botanica.software/blog/cryptographic-issues-in-cloudflares-circl-fourq-implementation
  NIST National Vulnerability Database

Elsewhere on this site

Related CVEs (same products)

• Medium CVE-2026-116497 Gssproxy: gssproxy: null pointer dereference in gssx_init_sec_context crashes daemon 2d
• Low CVE-2026-115449 Libslirp: libslirp: icmp echo reply length desynchronization leaks host ip to guest 5d
• Medium CVE-2026-115424 Oc: oc: symlink/hardlink target validation bypass in oc image extract allows file write outside destination 5d
• Medium CVE-2026-114406 Ca-certificates: distrust emudhra intermediate ca certificates due to security concerns 6d
• Low CVE-2026-114236 Podman: goroutine/file-descriptor leak in storage/pkg/archive.applylayer and applyuncompressedlayer on malformed layers 7d
• Medium CVE-2026-17557 Lm-evaluation-harness: lm-evaluation-harness: ssrf via job-spec model.url with bearer credential forwarding 7d

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 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-2025-8556 is "Github.com/cloudflare/circl: circl-fourq: missing and wrong validation can lead to incorrect results", rated Low. It affects Builds for Red Hat OpenShift (Red Hat); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 3.7 describes technical severity. EPSS 0.53% 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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