CVE-2026-103501

UNRATEDCVSS · not yet scoredTrending — 5 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: 0.2%CVSS v2: —Exploit: None knownExposed services: Not assessed

The CVE record names the fixed release — apply it.

Heap buffer overflow in the HLL sketch deserialization of Apache DataSketches C++ (repo: datasketches-cpp).

When deserializing a sketch in LIST mode, from either a byte buffer or a stream, the coupon count was read from the input and used as the number of entries to copy into a fixed buffer of 8 entries, without checking it against the buffer's capacity. A crafted sketch could cause a write of up to 988 bytes past the end of this internal heap buffer. This can corrupt heap memory, causing a crash and potentially enabling further exploitation.

This issue affects Apache DataSketches C++: from 1.0.0-incubating before 5.3.0. Only applications that deserialize HLL sketches 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
0.2%
EPSS %ILE
10th
KEV
Not listed

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” 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

October 10, 2026

Last Modified

October 13, 2026

Vendor Advisories for CVE-2026-103501(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 12× in last 7d / 12× 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 it from the CNA feed. 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). Most recent first.

  1. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  2. 2026-10-13 13:58 UTCGHSA enrichmentGHSA-w656-xfm5-jqjh
  3. 2026-10-12 16:40 UTCEG score recompute
  4. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  5. 2026-10-11 20:15 UTCEG score recompute
  6. 2026-10-11 18:28 UTCEG score recompute
  7. 2026-10-11 15:01 UTCEG score recompute
  8. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  9. 2026-10-10 13:23 UTCGHSA enrichmentGHSA-w656-xfm5-jqjh
  10. 2026-10-10 11:20 UTCNVD update
  11. 2026-10-10 10:37 UTCEG score recompute
  12. 2026-10-10 10:35 UTCMITRE cvelistV5first tracked

Frequently asked(4)

What is CVE-2026-103501?
CVE-2026-103501 is a vulnerability whose severity is not yet rated; its CVE record was published on October 10, 2026. Heap buffer overflow in the HLL sketch deserialization of Apache DataSketches C++ (repo: datasketches-cpp). When deserializing a sketch in LIST mode, from either a byte buffer or a stream, the coupon count was read from the input and used as the number of entries to copy into a fixed buffer of 8…
When was the CVE record for CVE-2026-103501 published?
The CVE record for CVE-2026-103501 was published on October 10, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 13, 2026; the record at its source may have been updated since.
Is CVE-2026-103501 actively exploited?
CVE-2026-103501 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (10th percentile of EPSS-scored CVEs).
How do I remediate CVE-2026-103501?
The CVE record for CVE-2026-103501 names the fix: "Users are recommended to upgrade to version 5.3.0, which fixes this issue." The vendor advisories EchelonGraph has for CVE-2026-103501 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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