CVE-2026-103636

UNRATEDCVSS · not yet scoredTrending — 4 sources updated this week
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EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No CVSS published and no exploitation signals yet
CISA-KEV: Not listedEPSS PROB: —CVSS v2: —Exploit: None knownExposed services: Not assessed

The CVE record names the fixed release — apply it.

Out-of-bounds read in the VarOpt union deserialization of Apache DataSketches C++ (repo: datasketches-cpp).

var_opt_union::deserialize() read the 32-byte preamble of a non-empty union after checking that only 8 bytes were available, so a truncated serialized union could cause a read of up to 24 bytes past the end of the input. For such inputs, the size remaining for the embedded sketch was also computed by an unsigned subtraction that could wrap around, so the embedded sketch's own size checks no longer limited reads to the input. The bytes read can become part of the deserialized union's state. This can cause a crash (denial of service) and could expose adjacent memory contents.

This issue affects Apache DataSketches C++: from 2.0.0-incubating before 5.3.0. Only applications that deserialize VarOpt unions from untrusted sources are affected.

Users are recommended to upgrade to version 5.3.0, which fixes this issue.

CVSS v3
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EchelonGraph score
Not yet assessedNo source has published severity data for this CVE yet — no CVSS score from NVD or a CNA, no GitHub advisory, and it is not in CISA KEV. This is not a rating of zero; we cannot assess it yet.
EG Score
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EG Risk
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EPSS PROB
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EPSS %ILE
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KEV
Not listed

Published

October 10, 2026

Last Modified

October 10, 2026

References (3)

Vendor Advisories for CVE-2026-103636(1)

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

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 4× in last 7d / 4× 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. 2026-10-10 13:23 UTCGHSA enrichment
  2. 2026-10-10 11:20 UTCNVD update
  3. 2026-10-10 10:37 UTCEG score recompute
  4. 2026-10-10 10:35 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(3)

What is CVE-2026-103636?
CVE-2026-103636 is a publicly disclosed vulnerability published on October 10, 2026. Out-of-bounds read in the VarOpt union deserialization of Apache DataSketches C++ (repo: datasketches-cpp). varoptunion::deserialize() read the 32-byte preamble of a non-empty union after checking that only 8 bytes were available, so a truncated serialized union could cause a read of up to 24 bytes…
When was CVE-2026-103636 disclosed?
CVE-2026-103636 was first published on October 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
How do I remediate CVE-2026-103636?
The CVE record for CVE-2026-103636 names the fix: "Users are recommended to upgrade to version 5.3.0, which fixes this issue." The vendor advisories EchelonGraph has for CVE-2026-103636 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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