CVE-2026-18540

LOWPre-NVD 3.73.7
EchelonGraph scoreMEDIUM confidence

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

This low-severity CVE scores 3.7 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-2026-71661 (ENISA EUVD) · GHSA-r53p-7pc4-xj5r (GitHub Security Advisories)Source: ENISA EUVD

3.7EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 3.7Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

undici's retry interceptor can append the body of a ranged retry response to bytes already delivered from an earlier partial response while still presenting the original response's status and headers. This happens when an upstream server delivers part of a body without a trustworthy resume checkpoint, for example a non-success response whose headers were already sent or a partial-content response with an unusable content range, then closes the connection and answers the resumed range request with more bytes. As a result the response body can be longer than the Content-Length that the application observes. An application that relays such a response to a downstream HTTP/1.1 peer without normalizing the framing can emit a body that exceeds the forwarded Content-Length, and the excess bytes can be interpreted as the start of a following response, which enables downstream response splitting or desynchronization. Exploitation requires an attacker-controlled upstream server and an application that forwards the response through a framing-sensitive path. This affects undici versions before 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.

CVSS v3
3.7
EG Score
3.7LOWmedium confidence
EG Risk
17
EG Risk 17/100

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)
Severity37% × 45%
Impact severity (EG Severity): CVSS 3.7 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (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.
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 (3.7): severity, escalated by confirmed exploitation. This CVE's 3.7 is its impact severity (EG Severity), not escalated.

EG Severity
3.7 LOWCVSS-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. 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 every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade 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 every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (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)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (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

September 4, 2026

Last Modified

September 16, 2026

References (2)

Vendor Advisories for CVE-2026-18540(5)

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

Patch Availability(3)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatnodejs24-main-11.19.0-1.24.21.0.1.hum12026-09-23redhat
redhatnodejs26-main-11.19.1-1.26.8.2.0.1.hum12026-09-11redhat
redhatgrafana12-4-main-12.4.10-0.2.hum12026-09-09redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(4 across 4 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
node-undici5.15.0+dfsg1+~cs20.10.9.3-1 ... 8.9.0+dfsg+~cs3.2.0-1 (40 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
node-undici7.15.0+dfsg+~cs3.2.0-1 ... 8.9.0+dfsg+~cs3.2.0-1 (16 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
node-undici7.15.0+dfsg+~cs3.2.0-1 ... 8.9.0+dfsg+~cs3.2.0-1 (15 versions)
  • every version up to 8.10.2+dfsg+~cs3.2.2-1: fixed in 8.10.2+dfsg+~cs3.2.2-1
—
npm(1)
PackageVulnerable rangeFix by version rangeDependents
undici—
  • every version up to 6.28.1: fixed in 6.28.1
  • 7.0.0 up to 7.29.1: fixed in 7.29.1
  • 8.0.0 up to 8.10.2: fixed in 8.10.2
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 46× 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.

  1. 2026-10-27 04:55 UTCOSV refresh
  2. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  3. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  4. 2026-10-25 14:45 UTCEG score recompute
  5. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  6. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  7. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  8. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  9. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  10. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  11. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  12. 2026-10-18 03:58 UTCEG score recompute
  13. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  14. 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  15. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  16. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  17. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  18. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  19. 2026-10-12 16:27 UTCEG score recompute
  20. 2026-10-11 20:07 UTCEG score recompute
  21. 2026-10-11 17:20 UTCEG score recompute
  22. 2026-10-11 14:52 UTCEG score recompute
  23. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  24. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  25. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.2% · 13th percentile
Show 51 more
  1. 2026-10-09 01:41 UTCEG score recompute
  2. 2026-10-09 01:41 UTCVendor advisory
  3. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  4. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  5. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  6. 2026-10-06 07:24 UTCEG score recompute
  7. 2026-10-06 07:24 UTCVendor advisory
  8. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  9. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  10. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  11. 2026-10-03 13:09 UTCEG score recompute
  12. 2026-10-03 13:09 UTCVendor advisory
  13. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  14. 2026-09-30 18:53 UTCEG score recompute
  15. 2026-09-30 18:53 UTCVendor advisory
  16. 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  17. 2026-09-29 15:20 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  18. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  19. 2026-09-27 22:21 UTCEG score recompute
  20. 2026-09-27 22:21 UTCVendor advisory
  21. 2026-09-27 13:47 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  22. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  23. 2026-09-25 04:05 UTCEG score recompute
  24. 2026-09-25 04:05 UTCVendor advisory
  25. 2026-09-22 09:50 UTCEG score recompute
  26. 2026-09-22 09:50 UTCVendor advisory
  27. 2026-09-19 15:33 UTCEG score recompute
  28. 2026-09-19 15:33 UTCVendor advisory
  29. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  30. 2026-09-16 21:10 UTCEG score recompute
  31. 2026-09-16 21:10 UTCVendor advisory
  32. 2026-09-16 14:07 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  33. 2026-09-16 05:14 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  34. 2026-09-14 08:28 UTCEG score recompute
  35. 2026-09-14 08:28 UTCVendor advisory
  36. 2026-09-13 16:46 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  37. 2026-09-12 15:00 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  38. 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  39. 2026-09-11 14:12 UTCEG score recompute
  40. 2026-09-11 14:12 UTCVendor advisory
  41. 2026-09-11 09:36 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  42. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  43. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  44. 2026-09-08 19:56 UTCEG score recompute
  45. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  46. 2026-09-07 14:23 UTCEG score recompute
  47. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  48. 2026-09-04 18:34 UTCEG score recompute
  49. 2026-09-04 17:55 UTCEG score recompute
  50. 2026-09-04 17:20 UTCEG score recomputeFirst assessed: 3.7 LOW
  51. 2026-09-04 17:19 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-18540?
CVE-2026-18540 is a low-severity vulnerability; its CVE record was published on September 4, 2026. undici's retry interceptor can append the body of a ranged retry response to bytes already delivered from an earlier partial response while still presenting the original response's status and headers. This happens when an upstream server delivers part of a body without a trustworthy resume…
When was the CVE record for CVE-2026-18540 published?
The CVE record for CVE-2026-18540 was published on September 4, 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 September 16, 2026; the record at its source may have been updated since.
Is CVE-2026-18540 actively exploited?
CVE-2026-18540 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-2026-18540?
CVE-2026-18540 has a CVSS base score of 3.7 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-18540?
A fix for CVE-2026-18540 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-18540 are linked in the Vendor Advisories panel on this page.

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