CVE-2026-27143 — Missing bound checks can lead to memory corruption in safe Go in cmd/compile
Arithmetic over induction variables in loops were not correctly checked for underflow or overflow. As a result, the compiler would allow for invalid indexing to occur at runtime, potentially leading to memory corruption.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.7% (30-day exploitation probability)+8
- Technical severity (critical)+10
- Automatable exploitation (SSVC)+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.
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.
- Documented patch — go.dev (NIST National Vulnerability Database)
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.
- Identify exposed assets running the affected vendor/product/version combinations (Go toolchain Cmd/compile, Golang Go).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Go toolchain | Cmd/compile | < 1.25.9≥ 1.26.0-0 and < 1.26.2 | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Golang | Go | < 1.25.9≥ 1.26.0 and < 1.26.2 | Vulnerable | NIST National Vulnerability Database |
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.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 9.8 | CVSS 3.1 | Critical | 3.9 | 5.9 | nvd@nist.gov via NIST National Vulnerability Database |
| 9.8 | CVSS 3.1 | Critical | 3.9 | 5.9 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database |
| 9.8 | CVSS 3.1 | Critical | — | — | CISA-ADP via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov) EPSS over time FIRST
Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 0.66%
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
- Affected products added · go toolchain/cmd/compile
- SSVC assessment updated
- Record published
- Fix documented
- CVSS changed · 9.8
- Source status changed · → Analyzed
- Record created in this database
- CVE published
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
Related CVEs (same products)
- Medium CVE-2026-42505 Invoking Encrypted Client Hello privacy leak in crypto/tls Jul 8, 2026
- High CVE-2026-39822 Root escape via symlink plus trailing slash in os Jul 8, 2026
- High CVE-2023-54365 Traefik - Denial of Service via HTTP/2 Request Handling Jun 23, 2026
- High CVE-2026-42501 Malicious module proxy can bypass checksum database in cmd/go May 7, 2026
- High CVE-2026-42499 Quadratic string concatenation in consumePhrase in net/mail May 7, 2026
- High CVE-2026-39820 Quadratic string concatentation in consumeComment in net/mail May 7, 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 CWE classification.
- 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-2026-27143 is "Missing bound checks can lead to memory corruption in safe Go in cmd/compile", rated Critical. It affects Cmd/compile (Go toolchain); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 0.66% 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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