CVE-2026-63209

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (28th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — Patch released this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

compress provides various compression algorithms. Prior to version 1.18.7, a signed integer overflow vulnerability in s2.NewDict() allows an attacker to bypass repeat index validation by supplying a dictionary with a uvarint-encoded repeat value exceeding MaxInt64. When Dict.Encode() is subsequently called, the overflowed negative repeat value causes an out-of-bounds memory access via unsafe.Pointer arithmetic, crashing the process with SIGSEGV. This issue has been patched in version 1.18.7.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
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
0.4%
EPSS %ILE
28th
KEV
Not listed

CISA SSVCTrack 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). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 29, 2026

Last Modified

September 30, 2026

Advisory Details (3)

Auto-updated Sep 29, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github.
github Patch Available🟡 PoC Available

Integer Overflow or Wraparound and Out-of-bounds Write in compress · Advisory · klauspost/compress · GitHub

https://github.com/klauspost/compress/security/advisories/GHSA-259r-337f-4rfw
github_release Patch Available

v1.18.7

Patch available: klauspost/compress v1.18.7

https://github.com/klauspost/compress/releases/tag/v1.18.7
github_commit

commit 539243b8823e (klauspost/compress)

Fix landed in klauspost/compress commit 539243b8823e — awaiting tagged release

https://github.com/klauspost/compress/commit/539243b8823ee8f03e49969823d57c348c917536

Vendor Advisories for CVE-2026-63209(20)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(24)

Vendor / EcosystemFixed in / PatchReleasedSource
redhattrivy-main-0.74.0-0.4.hum12026-09-28redhat
redhatloki3-6-main-3.6.17-0.3.hum12026-09-28redhat
redhatgrafana13-2-main-13.2.1-0.8.hum12026-09-28redhat
redhattempo3-0-main-3.0.3-0.4.hum12026-09-28redhat
redhatgrafana12-4-main-12.4.10-0.9.hum12026-09-28redhat
redhatspire1-15-main-1.15.3-0.2.hum12026-09-28redhat
redhattempo2-10-main-2.10.8-0.4.hum12026-09-28redhat
redhatloki3-7-main-3.7.8-0.3.hum12026-09-28redhat
redhatgrafana13-1-main-13.1.6-0.4.hum12026-09-28redhat
redhatbuildah-main-1.45.1-1.hum12026-09-23redhat
redhatskopeo-main-1.24.1-1.hum12026-09-23redhat
redhatpodman-main-6.1.2-1.hum12026-09-23redhat
redhatk6v2-main-2.3.0-0.1.hum12026-09-22redhat
redhatgrype-main-0.119.0-0.1.hum12026-09-18redhat
redhatsyft-main-1.52.0-0.1.hum12026-09-18redhat
redhathelm4-main-4.3.0-0.2.hum12026-09-17redhat
redhathelm3-main-3.22.0-0.2.hum12026-09-17redhat
redhatopentelemetry-collector-k8s-main-0.161.0-0.1.hum12026-09-17redhat
redhatopentelemetry-collector-main-0.161.0-0.1.hum12026-09-16redhat
redhatopentelemetry-collector-contrib-main-0.161.0-0.1.hum12026-09-16redhat
redhatnats-server2-14-main-2.14.7-0.1.hum12026-09-16redhat
redhatrekor-main-1.5.4-0.1.hum12026-08-22redhat
redhatk6v1-main-1.8.1-0.1.hum12026-08-12redhat
redhatnats-server2-12-main-2.12.15-0.1.hum12026-08-12redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFixed inDependents
github.com/klauspost/compress—1.18.7—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(5)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 17× in last 7d / 17× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-10-04 07:44 UTCVendor advisory
  2. 2026-10-03 19:47 UTCEG score recompute
  3. 2026-10-03 19:47 UTCVendor advisory
  4. 2026-10-03 14:26 UTCEPSS rescore
  5. 2026-10-03 07:50 UTCVendor advisory
  6. 2026-10-02 19:50 UTCEG score recompute
  7. 2026-10-02 19:50 UTCVendor advisory
  8. 2026-10-02 17:56 UTCEPSS rescore
  9. 2026-10-01 19:55 UTCEG score recompute
  10. 2026-10-01 19:50 UTCEPSS rescore
  11. 2026-09-30 17:29 UTCEG score recompute
  12. 2026-09-30 15:03 UTCEPSS rescore
  13. 2026-09-29 17:32 UTCEG score recompute
  14. 2026-09-29 16:45 UTCEG score recompute
  15. 2026-09-29 15:23 UTCEG score recompute
  16. 2026-09-29 15:09 UTCEG score recompute
  17. 2026-09-29 15:08 UTCMITRE cvelistV5first tracked

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-63209?
CVE-2026-63209 is a high vulnerability published on September 29, 2026. compress provides various compression algorithms. Prior to version 1.18.7, a signed integer overflow vulnerability in s2.NewDict() allows an attacker to bypass repeat index validation by supplying a dictionary with a uvarint-encoded repeat value exceeding MaxInt64. When Dict.Encode() is…
When was CVE-2026-63209 disclosed?
CVE-2026-63209 was first published on September 29, 2026, with the most recent update on September 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63209 actively exploited?
CVE-2026-63209 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (28th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-63209?
CVE-2026-63209 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-63209?
A fix for CVE-2026-63209 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-63209 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-63209

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