CVE-2026-123338

UNRATEDCVSS · not yet scored

Also known asEUVD-2026-125274 (ENISA EUVD) · GHSA-f29r-h9w7-gp62 (GitHub Security Advisories)Source: ENISA EUVD

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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 Write vulnerability in Apache DataSketches C++. An application that deserializes a REQ sketch from an untrusted source can have heap memory corrupted by a crafted sketch, because the serialized compactor headers were not validated.

This issue affects Apache DataSketches C++: from 3.0.0 through 5.3.0.

Users are recommended to upgrade to version 5.3.1, which fixes the issue.

CVSS
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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

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

EG Severity
Not assessed: no CVSS publishedA missing CVSS is not a severity of zero.
EG Likelihood
Unknown (no EPSS on record)Unknown, not low: FIRST has published no EPSS probability for this CVE.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
No SSVC decision: EchelonGraph has not assessed this CVECISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the BOD 26-04 block below.

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.

The score's inputs: 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

November 13, 2026

Last Modified

November 13, 2026

References (5)

Vendor Advisories for CVE-2026-123338(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 3× in last 7d / 3× 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 → 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.

  1. 2026-11-13 12:58 UTCGHSA enrichmentGHSA-f29r-h9w7-gp62
  2. 2026-11-13 11:01 UTCENISA EUVD ID recordedEUVD-2026-125274 · Source: ENISA EUVD
  3. 2026-11-13 10:37 UTCEchelonGraph re-scored
  4. 2026-11-13 10:36 UTCMITRE cvelistV5first tracked

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Frequently asked(3)

What is CVE-2026-123338?
CVE-2026-123338 is a vulnerability whose severity is not yet rated; its CVE record was published on November 13, 2026. Out-of-bounds Write vulnerability in Apache DataSketches C++. An application that deserializes a REQ sketch from an untrusted source can have heap memory corrupted by a crafted sketch, because the serialized compactor headers were not validated. This issue affects Apache DataSketches C++: from…
When was the CVE record for CVE-2026-123338 published?
The CVE record for CVE-2026-123338 was published on November 13, 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 November 13, 2026; the record at its source may have been updated since.
How do I remediate CVE-2026-123338?
The CVE record for CVE-2026-123338 names the fix: "Users are recommended to upgrade to version 5.3.1, which fixes the issue." The vendor advisories EchelonGraph has for CVE-2026-123338 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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