CVE-2026-104254

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% (21st 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

Also known asEUVD-2026-118512 (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. From 0.11.0 through 0.16.0, builds configured with OQS_ENABLE_SIG_STFL_LMS=ON can read beyond a caller-supplied signature buffer when an untrusted truncated LMS or HSS-LMS signature reaches OQS_SIG_STFL_verify or OQS_SIG_STFL_alg_lms_verify. In hss_validate_signature_init() in src/sig_stfl/lms/external/hss_verify_inc.c, consumed-length checks do not ensure that the bottom-level q and C fields remain available, allowing up to 32 bytes to be read past the buffer. In version 0.16.0, is_hss_public_key() also reads at offset 8 after only a four-byte length check, allowing an over-read of up to eight bytes. No valid signature is required, but the public key must be syntactically plausible. The read data is consumed only by an internal hash and is not exposed, so the supported impact is a possible verifier crash and denial of service, not memory disclosure or acceptance of an invalid signature. This issue is scheduled to be fixed in version 0.17.0.

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
21st
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 2026-11-12). 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, and whom BOD 26-04 binds: 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.

The score's inputs: 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

November 6, 2026

Last Modified

November 12, 2026

Advisory Details (3)

Auto-updated Nov 6, 2026
Fix named in the CVE record. Sources: github, github_commit, github_pr.
GitHub commit

commit df3eb80fe68d (open-quantum-safe/liboqs)

Fix landed in open-quantum-safe/liboqs commit df3eb80fe68d — awaiting tagged release

https://github.com/open-quantum-safe/liboqs/commit/df3eb80fe68d2e5db0ecf5d503082cd5699e0859
GitHub pull request

Fix out-of-bounds read in hss_validate_signature_init

Fix merged in open-quantum-safe/liboqs PR #2507 on 2026-09-09 — awaiting tagged release

https://github.com/open-quantum-safe/liboqs/pull/2507
GitHub advisoryMentions a patch (unverified)

Heap out-of-bounds read in LMS/HSS signature verification via unvalidated signature length · Advisory · open-quantum-safe/liboqs · GitHub

Affected: version 0.17.0 (to be released) and on the main branch of liboqs on GitHub.

https://github.com/open-quantum-safe/liboqs/security/advisories/GHSA-wh5q-mpc8-67wf

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 9× 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 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). "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 16:50 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  2. 2026-11-12 22:31 UTCEchelonGraph re-scored
  3. 2026-11-12 16:32 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  4. 2026-11-11 16:37 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  5. 2026-11-10 16:41 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  6. 2026-11-09 23:48 UTCEchelonGraph re-scored
  7. 2026-11-09 22:50 UTCEchelonGraph re-scored
  8. 2026-11-09 16:34 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  9. 2026-11-08 16:38 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  10. 2026-11-07 16:38 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  11. 2026-11-06 22:27 UTCEchelonGraph re-scored
  12. 2026-11-06 22:04 UTCENISA EUVD ID recordedEUVD-2026-118512 · Source: ENISA EUVD
  13. 2026-11-06 21:26 UTCEchelonGraph re-scoredFirst assessed: 5.3 MEDIUM
  14. 2026-11-06 21:26 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-104254?
CVE-2026-104254 is a medium-severity vulnerability; its CVE record was published on November 6, 2026. liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. From 0.11.0 through 0.16.0, builds configured with OQS_ENABLE_SIG_STFL_LMS=ON can read beyond a caller-supplied signature buffer when an untrusted truncated LMS or HSS-LMS signature…
When was the CVE record for CVE-2026-104254 published?
The CVE record for CVE-2026-104254 was published on November 6, 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 12, 2026; the record at its source may have been updated since.
Is CVE-2026-104254 actively exploited?
CVE-2026-104254 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (21st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-104254?
CVE-2026-104254 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-2026-104254?
The CVE record for CVE-2026-104254 names the fix: "This issue is scheduled to be fixed in version 0.17.0."

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-104254

Explore →

Is Your Infrastructure Affected by CVE-2026-104254?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs