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.
CVE-2026-63209
“—” beside the score: it is equal to the CVSS score beside it.
Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-10-20. A secondary CVSS source baseline 7.5; sources differ by 0.0.
Also known asEUVD-2026-88977 (ENISA EUVD) · GHSA-259r-337f-4rfw (GitHub Security Advisories) · GO-2026-5841 (OSV.dev)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5HIGHhigh confidence
- EG Risk
- 49EG Risk 49/100
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)Severity75% × 45%Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.6% × 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
- 47th
- 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 (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.5 HIGHCVSS-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 (model v2026.06.15, score date 2026-11-12). 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
September 29, 2026
Last Modified
September 30, 2026
Advisory Details (3)
Auto-updated Sep 29, 2026Integer Overflow or Wraparound and Out-of-bounds Write in compress · Advisory · klauspost/compress · GitHub
https://github.com/klauspost/compress/security/advisories/GHSA-259r-337f-4rfwv1.18.7
Patch available: klauspost/compress v1.18.7
https://github.com/klauspost/compress/releases/tag/v1.18.7commit 539243b8823e (klauspost/compress)
Fix landed in klauspost/compress commit 539243b8823e — awaiting tagged release
https://github.com/klauspost/compress/commit/539243b8823ee8f03e49969823d57c348c917536Vendor 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.
- RHSA-2026:95612Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Compliance Operator bug fix and enhancement update
- RHSA-2026:95591Red Hat Product SecurityHigh
Red Hat Security Advisory: Cluster Observability Operator - 1.5
- RHSA-2026:95517Red Hat Product SecurityHigh
Red Hat Security Advisory: Multicluster Global Hub 1.7.4 security update
- RHSA-2026:95081Red Hat Product SecurityHigh
Red Hat Security Advisory: Cluster Observability Operator - 1.5
- RHSA-2026:94498Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat OpenShift API for Data Protection - 1.4.12
- RHSA-2026:92994Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Container Platform 4.21.41 bug fix and security update
- RHSA-2026:92593Red Hat Product SecurityHigh
Red Hat Security Advisory: Logging for Red Hat OpenShift - 6.6.2
- RHSA-2026:92515Red Hat Product SecurityHigh
Red Hat Security Advisory: Logging for Red Hat OpenShift - 6.6.2
- +12 more
Patch Availability(30)
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
(3 across 3 ecosystems)
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| golang-github-klauspost-compress | 1.18.0+ds1-1 ... 1.20.0+ds1-1 (7 versions) |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| golang-github-klauspost-compress | 1.18.0+ds1-1, 1.18.1+ds1-1, 1.18.6+ds1-1, 1.18.6+ds1-2 |
| — |
Go(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| github.com/klauspost/compress | — |
| — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Additional Vendor Advisories
(24)
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.
- Red HatRHSA-2026:54413IMPORTANT2026-09-29
RHSA-2026:54413 — Important
- Red HatRHSA-2026:54419IMPORTANT2026-09-29
RHSA-2026:54419 — Important
- Red HatRHSA-2026:58472IMPORTANT2026-09-29
RHSA-2026:58472 — Important
- Red HatRHSA-2026:68256IMPORTANT2026-09-29
RHSA-2026:68256 — Important
- Red HatRHSA-2026:68272IMPORTANT2026-09-29
RHSA-2026:68272 — Important
- Red HatRHSA-2026:68290IMPORTANT2026-09-29
RHSA-2026:68290 — Important
- Red HatRHSA-2026:68591IMPORTANT2026-09-29
RHSA-2026:68591 — Important
- Red HatRHSA-2026:68717IMPORTANT2026-09-29
RHSA-2026:68717 — Important
- Red HatRHSA-2026:68729IMPORTANT2026-09-29
RHSA-2026:68729 — Important
- Red HatRHSA-2026:68806IMPORTANT2026-09-29
RHSA-2026:68806 — Important
- Red HatRHSA-2026:68808IMPORTANT2026-09-29
RHSA-2026:68808 — Important
- Red HatRHSA-2026:70031IMPORTANT2026-09-29
RHSA-2026:70031 — Important
- Red HatRHSA-2026:70670IMPORTANT2026-09-29
RHSA-2026:70670 — Important
- Red HatRHSA-2026:70684IMPORTANT2026-09-29
RHSA-2026:70684 — Important
- Red HatRHSA-2026:70726IMPORTANT2026-09-29
RHSA-2026:70726 — Important
- Red HatRHSA-2026:72490IMPORTANT2026-09-29
RHSA-2026:72490 — Important
- Red HatRHSA-2026:72491IMPORTANT2026-09-29
RHSA-2026:72491 — Important
- Red HatRHSA-2026:72492IMPORTANT2026-09-29
RHSA-2026:72492 — Important
- Red HatRHSA-2026:72493IMPORTANT2026-09-29
RHSA-2026:72493 — Important
- Red HatRHSA-2026:72496IMPORTANT2026-09-29
RHSA-2026:72496 — Important
- Red HatRHSA-2026:72497IMPORTANT2026-09-29
RHSA-2026:72497 — Important
- Red HatRHSA-2026:72498IMPORTANT2026-09-29
RHSA-2026:72498 — Important
- Red HatRHSA-2026:72507IMPORTANT2026-09-29
RHSA-2026:72507 — Important
- Red HatRHSA-2026:72570IMPORTANT2026-09-29
RHSA-2026:72570 — Important
Data Freshness Timeline
(refreshed 9× in last 7d / 37× 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 its CVE.org record (CNA or CISA ADP). 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). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.
- 2026-11-13 01:54 UTCEchelonGraph re-scored
- 2026-11-13 01:54 UTCVendor advisory
- 2026-11-13 01:54 UTCGHSA enrichmentGHSA-259r-337f-4rfw · GitHub severity HIGH · GitHub CVSS 7.5
- 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-11-05 12:14 UTCEchelonGraph re-scored
- 2026-11-05 12:14 UTCVendor advisory
- 2026-11-05 12:14 UTCGHSA enrichmentGHSA-259r-337f-4rfw · GitHub severity HIGH · GitHub CVSS 7.5
- 2026-11-04 16:36 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-11-03 16:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-11-01 07:41 UTCGHSA enrichmentGHSA-259r-337f-4rfw · GitHub severity HIGH · GitHub CVSS 7.5
- 2026-11-01 07:41 UTCEchelonGraph re-scored
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-28 22:33 UTCEchelonGraph re-scored
- 2026-10-28 21:25 UTCOSV refresh
Show 74 moreShow fewer
- 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-25 14:13 UTCEchelonGraph re-scored
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.4% · 29th percentile
- 2026-10-21 01:43 UTCEchelonGraph re-scored
- 2026-10-21 01:43 UTCVendor advisory
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-18 03:23 UTCEchelonGraph re-scored
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-13 12:03 UTCEchelonGraph re-scored
- 2026-10-13 12:03 UTCVendor advisory
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-12 15:49 UTCEchelonGraph re-scored
- 2026-10-11 19:33 UTCVendor advisory
- 2026-10-11 19:33 UTCEchelonGraph re-scored
- 2026-10-11 16:48 UTCEchelonGraph re-scored
- 2026-10-11 14:10 UTCEchelonGraph re-scored
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-11 07:36 UTCEchelonGraph re-scored
- 2026-10-11 07:36 UTCVendor advisory
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-10 19:39 UTCVendor advisory
- 2026-10-10 07:42 UTCEchelonGraph re-scored
- 2026-10-10 07:42 UTCVendor advisory
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-09 19:45 UTCVendor advisory
- 2026-10-09 07:48 UTCVendor advisory
- 2026-10-08 19:50 UTCEchelonGraph re-scored
- 2026-10-08 19:50 UTCVendor advisory
- 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-08 07:28 UTCEchelonGraph re-scored
- 2026-10-08 07:28 UTCVendor advisory
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-07 19:31 UTCVendor advisory
- 2026-10-07 07:25 UTCVendor advisory
- 2026-10-06 19:28 UTCEchelonGraph re-scored
- 2026-10-06 19:28 UTCVendor advisory
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-06 07:31 UTCVendor advisory
- 2026-10-05 19:34 UTCEchelonGraph re-scored
- 2026-10-05 19:34 UTCVendor advisory
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-05 07:38 UTCEchelonGraph re-scored
- 2026-10-05 07:38 UTCVendor advisory
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-04 19:41 UTCVendor advisory
- 2026-10-04 07:44 UTCVendor advisory
- 2026-10-03 19:47 UTCEchelonGraph re-scored
- 2026-10-03 19:47 UTCVendor advisory
- 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-03 07:50 UTCVendor advisory
- 2026-10-02 19:50 UTCEchelonGraph re-scored
- 2026-10-02 19:50 UTCVendor advisory
- 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-01 19:55 UTCEchelonGraph re-scored
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-09-30 17:29 UTCEchelonGraph re-scored
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-09-29 17:32 UTCEchelonGraph re-scored
- 2026-09-29 16:45 UTCEchelonGraph re-scored
- 2026-09-29 15:23 UTCEchelonGraph re-scored
- 2026-09-29 15:09 UTCEchelonGraph re-scoredFirst assessed: 7.5 HIGH
- 2026-09-29 15:08 UTCMITRE cvelistV5first tracked
Related CVEs(same product + same vendor + same CWE)
Same vendor
10 shownredhat:RHSA-2026:68272 · redhat:RHSA-2026:79368 · redhat:RHSA-2026:83013
Frequently asked(5)
What is CVE-2026-63209?
When was the CVE record for CVE-2026-63209 published?
Is CVE-2026-63209 actively exploited?
What is the CVSS score of CVE-2026-63209?
How do I remediate CVE-2026-63209?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-63209
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