CVE-2026-126360

MEDIUMPre-NVD 5.35.3
EchelonGraph scoreLOW confidence

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (44th 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: a secondary CVSS source

Also known asEUVD-2026-124741 (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: 0.5%CVSS: 5.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

OpenTelemetry Python provides the Python API and SDK for OpenTelemetry. Prior to 1.45.2, TraceContextTextMapPropagator.extract() in opentelemetry-api can perform quadratic-time regular-expression backtracking on a malformed traceparent value containing a trace-context prefix, a long whitespace sequence, and an embedded newline. Exploitation requires an attacker-controlled carrier that preserves embedded newlines and permits a sufficiently large value, because conforming HTTP header values cannot contain embedded newlines. JSON-based carriers, including applicable MCP request metadata integrations, can preserve the required newline depending on the SDK, instrumentation, and message-size limits. Parsing on an asynchronous server's event-loop thread can consume excessive CPU and delay unrelated requests, while the advisory does not establish disclosure, modification, or code execution. This issue is fixed in version 1.45.2.

CVSS v3
5.3
EG Score
5.3MEDIUMlow 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% × 40%
No KEV listing, EG-KEV tier or EPSS 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: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
44th
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
0.5% within 30 daysSource: FIRST EPSS. 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).

A fix is available. 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 12, 2026

Last Modified

November 13, 2026

Advisory Details (6)

Auto-updated Nov 13, 2026
Patch available. Sources: github, github_commit, github_pr, github_release.
GitHub advisoryMentions a patch (unverified)

Denial of service through quadratic-time traceparent parsing in opentelemetry-api · Advisory · open-telemetry/opentelemetry-python · GitHub

https://github.com/open-telemetry/opentelemetry-python/security/advisories/GHSA-mf5v-w3w3-f6cg
GitHub release Patch Available

Version 1.45.2/0.66b2

Patch available: open-telemetry/opentelemetry-python v1.45.2

https://github.com/open-telemetry/opentelemetry-python/releases/tag/v1.45.2
GitHub pull request Patch Available

[release/v1.45.x-0.66bx] Backport metric cardinality limits and traceparent parsing

Patch available: open-telemetry/opentelemetry-python v1.45.2 (PR #5856 merged 2026-10-29)

https://github.com/open-telemetry/opentelemetry-python/pull/5856
GitHub pull request

opentelemetry-api: refine traceparent parsing

Fix merged in open-telemetry/opentelemetry-python PR #5818 on 2026-10-26 — awaiting tagged release

https://github.com/open-telemetry/opentelemetry-python/pull/5818
GitHub commit

commit faa72dae511a (open-telemetry/opentelemetry-python)

Fix landed in open-telemetry/opentelemetry-python commit faa72dae511a — awaiting tagged release

https://github.com/open-telemetry/opentelemetry-python/commit/faa72dae511ae64a7bf8ca63eff9ad4387d0b939
GitHub commit Patch Available

commit 78123a2755c9 (open-telemetry/opentelemetry-python)

Patch available: open-telemetry/opentelemetry-python v1.45.2 (contains commit 78123a2755c9)

https://github.com/open-telemetry/opentelemetry-python/commit/78123a2755c907c602e02352aebed4be86aa5350

Vendor Advisories for CVE-2026-126360(1)

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

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
opentelemetry-api0.10b0 ... 1.9.1 (86 versions)
  • every version up to 1.45.2: fixed in 1.45.2
—

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 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 0.5% · 44th percentile
  2. 2026-11-13 02:28 UTCEchelonGraph re-scored
  3. 2026-11-13 00:52 UTCEchelonGraph re-scored
  4. 2026-11-13 00:28 UTCEchelonGraph re-scored
  5. 2026-11-12 23:01 UTCENISA EUVD ID recordedEUVD-2026-124741 · Source: ENISA EUVD
  6. 2026-11-12 22:27 UTCEchelonGraph re-scoredFirst assessed: 5.3 MEDIUM
  7. 2026-11-12 22:26 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-126360?
CVE-2026-126360 is a medium-severity vulnerability; its CVE record was published on November 12, 2026. OpenTelemetry Python provides the Python API and SDK for OpenTelemetry. Prior to 1.45.2, TraceContextTextMapPropagator.extract() in opentelemetry-api can perform quadratic-time regular-expression backtracking on a malformed traceparent value containing a trace-context prefix, a long whitespace…
When was the CVE record for CVE-2026-126360 published?
The CVE record for CVE-2026-126360 was published on November 12, 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.
Is CVE-2026-126360 actively exploited?
CVE-2026-126360 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (44th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-126360?
CVE-2026-126360 has a CVSS base score of 5.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-126360?
A fix for CVE-2026-126360 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-126360 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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