CVE Intelligence
Medium Memory corruption

CVE-2026-103634 — Apache DataSketches: datasketches-cpp: Out-of-bounds read and write in Count-Min sketch deserialization allows memory corruption via a crafted sketch

Out-of-bounds read and write in the Count-Min sketch deserialization of Apache DataSketches C++ (repo: datasketches-cpp). count_min_sketch::deserialize() did not include the preamble in its input size check, so a truncated sketch could cause a read of up to 16 bytes past the end of the input. In addition, the table size was computed from the serialized number of buckets and number of hash functions in 32-bit arithmetic. A crafted sketch could make it wrap to zero, so that the sketch deserialized with an empty table, and later updates and estimate queries read and wrote outside the heap allocation. This can corrupt heap memory, causing a crash and potentially enabling further exploitation. This issue affects Apache DataSketches C++: from 4.1.0 before 5.3.0. Only applications that deserialize Count-Min sketches from untrusted sources are affected. Users are recommended to upgrade to version 5.3.0, which fixes this issue.

Published Oct 22, 2026 · Updated Oct 26, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: apache

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.5% (30-day exploitation probability)+6
  • Technical severity (medium)+3
  • Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.49%
ahead of 42% of scored CVEs · Oct 30, 2026
Affects
Apache Software Foundation
Apache DataSketches
CVSS base
5.3
Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Apache Software Foundation Apache DataSketches).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Apache Software Foundation Apache DataSketches ≥ 4.1.0 and ≤ 5.2.0 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
5.3 CVSS 3.1 Medium 3.9 1.4 134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database
5.3 CVSS 3.1 Medium — — CISA-ADP via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L (score shown at the top: 134c704f-9b21-4f2e-91b3-4a467353bcc0)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-190 · Integer Overflow or Wraparound

Other CVEs with this weakness →

EPSS over time FIRST

Oct 22, 2026 → Oct 30, 2026 · 9 reading(s) · max 0.49%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • SSVC assessment updated
    Oct 26, 2026 · CVE Program (cve.org) e CISA ADP
  • CVSS changed · 5.3
    Oct 26, 2026 · NIST National Vulnerability Database
  • Source status changed · Received → Awaiting Analysis
    Oct 22, 2026 · NIST National Vulnerability Database
  • Record published
    Oct 22, 2026
  • Affected products added · apache software foundation/apache datasketches
    Oct 22, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Received
    Oct 22, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 22, 2026 · Alertas do Telegram
  • CVE published
    Oct 22, 2026 · apache

Source activity

Repeated readings are counted rather than listed.

  • 3× References added · Oct 22, 2026 – Oct 26, 2026
  • 1× Official description updated · Oct 22, 2026 – Oct 22, 2026

References

5 on the record

Elsewhere on this site

Apache Software Foundation
every CVE for this vendor
Memory corruption
same class
CWE-190
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-103636 Apache DataSketches: datasketches-cpp: Out-of-bounds read in VarOpt union deserialization allows denial of service via a truncated sketch 21d
  • CVE-2026-103635 Apache DataSketches: datasketches-cpp: Out-of-bounds read in compact Theta sketch deserialization allows denial of service via a crafted sketch 21d
  • CVE-2026-103513 Apache DataSketches: datasketches-cpp: Out-of-bounds read and write in the CPC sketch deserialization allows memory corruption via a crafted sketch 21d
  • CVE-2026-103501 Apache DataSketches: datasketches-cpp: HLL CouponList Deserialization Buffer Overflow allows memory corruption via a crafted sketch 21d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-103634 is "Apache DataSketches: datasketches-cpp: Out-of-bounds read and write in Count-Min sketch deserialization allows memory corruption via a crafted sketch", rated Medium. It affects Apache DataSketches (Apache Software Foundation); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.3 describes technical severity. EPSS 0.49% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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