CVE-2026-44518

MEDIUMPre-NVD 5.35.3
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (23rd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Trending — 3 sources updated this week

Also known asEUVD-2026-33412 (ENISA EUVD)Source: ENISA EUVD

5.3EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 5.3Exploit: None knownExposed services: Not assessed

The CVE record names the fixed release — apply it.

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Prior to 0.16.0, an out-of-bounds read has been identified in the XMSS and XMSS^MT stateful signature verification code. When the verification function is called with a signature buffer shorter than the expected signature size for the given parameter set, the implementation does not validate the caller-supplied length and proceeds to read past the end of the buffer. The out-of-bounds bytes are consumed only as input to an internal hash computation and are not returned to the caller, so no oracle exists to leak their contents to an attacker. The primary observable effect is a possible crash (denial of service) of the verifying process if the read crosses into an unmapped memory page. This vulnerability is fixed in 0.16.0.

CVSS v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
39
EG Risk 39/100

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)
Severity53% × 45%
Impact severity (EG Severity): CVSS 5.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.3% × 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: The CVE record names the fixed release. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.3%
EPSS %ILE
23rd
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 (5.3): severity, escalated by confirmed exploitation. This CVE's 5.3 is its impact severity (EG Severity), not escalated.

EG Severity
5.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). 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: 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).

The CVE record names the fixed release. 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.

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

May 29, 2026

Last Modified

July 21, 2026

Advisory Details (2)

Auto-updated Jun 16, 2026
Fix named in the CVE record. Sources: github_commit, github.
GitHub advisoryMentions a patch (unverified)

XMSS Buffer Overread Bug · Advisory · open-quantum-safe/liboqs · GitHub

Affected: version 0.16.0 (to be released) and the main branch of liboqs on GitHub.

https://github.com/open-quantum-safe/liboqs/security/advisories/GHSA-wf7v-fhxj-73m2
GitHub commit

commit ef70dea7c85e (open-quantum-safe/liboqs)

Fix landed in open-quantum-safe/liboqs commit ef70dea7c85e — awaiting tagged release

https://github.com/open-quantum-safe/liboqs/commit/ef70dea7c85e5637f37828d75e5b9bb29dbfe513

Weakness Classification(2)

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

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 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.

Showing the most recent 100 of 185 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 85 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  2. 2026-10-30 16:25 UTCOSV refresh
  3. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
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  8. 2026-10-25 14:27 UTCEG score recompute
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  11. 2026-10-22 23:47 UTCEG score recompute
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  17. 2026-10-18 03:39 UTCEG score recompute
  18. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.3% · 21st percentile
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  24. 2026-10-12 16:05 UTCEG score recompute
  25. 2026-10-11 19:47 UTCEG score recompute
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  1. 2026-10-11 17:01 UTCEG score recompute
  2. 2026-10-11 14:27 UTCEG score recompute
  3. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  4. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.3% · 21st percentile
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  7. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  8. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  9. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  10. 2026-10-03 14:48 UTCOSV refresh
  11. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  12. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  13. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  14. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.3% · 20th percentile
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  22. 2026-09-14 06:24 UTCEG score recompute
  23. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  24. 2026-09-13 01:06 UTCOSV refresh
  25. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
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  40. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  41. 2026-08-25 04:19 UTCEG score recompute
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  43. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
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  45. 2026-08-21 15:08 UTCEG score recompute
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  51. 2026-08-17 06:52 UTCEG score recompute
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Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-44518?
CVE-2026-44518 is a medium-severity vulnerability; its CVE record was published on May 29, 2026. liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Prior to 0.16.0, an out-of-bounds read has been identified in the XMSS and XMSS^MT stateful signature verification code. When the verification function is called with a signature…
When was the CVE record for CVE-2026-44518 published?
The CVE record for CVE-2026-44518 was published on May 29, 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 July 21, 2026; the record at its source may have been updated since.
Is CVE-2026-44518 actively exploited?
CVE-2026-44518 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (23rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-44518?
CVE-2026-44518 has a CVSS base score of 5.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-44518?
The CVE record for CVE-2026-44518 names the fix: "This vulnerability is fixed in 0.16.0."

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