CVE-2026-87864

HIGHPre-NVD 8.18.1
EchelonGraph scoreHIGH confidence

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

Score 8.1 from GitHub Security Advisory (severity: HIGH) published 2026-10-20. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 8.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: CISA-ADP (Vulnrichment) CVSS v3.1, EPSS, GitHub Security Advisory
Elevated

Also known asEUVD-2026-105310 (ENISA EUVD) · GHSA-mxp6-wxxv-r9rj (GitHub Security Advisories)Source: ENISA EUVD

8.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.8%CVSS: 8.1Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

Enabling CURLOPT_CRLF causes curl to advertise the raw input byte count in the IMAP APPEND {N} literal while transmitting line-ending expanded data. The server reads only $N$ bytes for the payload, causing the remaining overflow bytes to be interpreted and executed as pipelined IMAP commands within the authenticated session.

CVSS v3
8.1
EG Score
8.1HIGHhigh confidence
EG Risk
52
EG Risk 52/100

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)
Severity81% × 45%
Impact severity (EG Severity): CVSS 8.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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
0.8%
EPSS %ILE
57th
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 (8.1): severity, escalated by confirmed exploitation. This CVE's 8.1 is its impact severity (EG Severity), not escalated.

EG Severity
8.1 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.8% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-06). 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, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade 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, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (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

October 20, 2026

Last Modified

October 30, 2026

Advisory Details (3)

Auto-updated Oct 30, 2026
Patch available.
Web page

HackerOne

https://hackerone.com/reports/3972403
Web page
https://curl.se/docs/CVE-2026-87864.json
Web page

curl - IMAP APPEND plus CRLF conversion command injection - CVE-2026-87864

https://curl.se/docs/CVE-2026-87864.html

Vendor Advisories for CVE-2026-87864(3)

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

Patch Availability(4)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibcurl4t64 (8.18.0-1ubuntu2.8) @ resolute2026-10-22ubuntu
ubuntulibcurl4-openssl-dev (7.47.0-1ubuntu2.19+esm21) @ xenial2026-10-22ubuntu
ubuntulibcurl4t64 (8.20.0-2ubuntu11.1) @ stonking2026-10-22ubuntu
redhatcurl-main-8.23.0-0.1.hum12026-10-14redhat

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

(5 across 5 ecosystems)
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 8.23.0-r0: fixed in 8.23.0-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 8.23.0-r0: fixed in 8.23.0-r0
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
curl7.88.1-10 ... 8.9.1-2~bpo12+1 (187 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
curl8.14.1-2 ... 8.23.0~rc3-1+exp1 (88 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
curl8.14.1-2 ... 8.22.0~rc3-1+exp1 (72 versions)
  • every version up to 8.22.0-1: fixed in 8.22.0-1
—

Weakness Classification(1)

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

Additional Vendor Advisories

(3)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 9× in last 7d / 36× 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. 2026-11-12 16:35 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  2. 2026-11-11 16:41 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  3. 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  4. 2026-11-09 16:36 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  5. 2026-11-08 16:41 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  6. 2026-11-07 16:40 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  7. 2026-11-06 16:41 UTCEchelonGraph re-scored
  8. 2026-11-06 16:41 UTCVendor advisory
  9. 2026-11-06 16:41 UTCGHSA enrichmentGHSA-mxp6-wxxv-r9rj · GitHub severity HIGH · GitHub CVSS 8.1
  10. 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  11. 2026-11-05 16:39 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  12. 2026-11-04 16:37 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  13. 2026-11-03 16:49 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  14. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  15. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  16. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  17. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  18. 2026-10-30 12:25 UTCEchelonGraph re-scored
  19. 2026-10-30 12:25 UTCVendor advisory
  20. 2026-10-30 12:25 UTCGHSA enrichmentGHSA-mxp6-wxxv-r9rj
  21. 2026-10-30 12:15 UTCEchelonGraph re-scoredFirst assessed: 8.1 HIGH
  22. 2026-10-30 12:15 UTCVendor advisory
  23. 2026-10-30 12:15 UTCGHSA enrichmentGHSA-mxp6-wxxv-r9rj
  24. 2026-10-30 12:14 UTCMITRE cvelistV5CVSS v3 → 8.1 · severity → HIGH
  25. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.2% · 12th percentile
Show 17 more
  1. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  2. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  3. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  4. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  5. 2026-10-25 13:53 UTCEchelonGraph re-scored
  6. 2026-10-24 16:34 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  7. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  8. 2026-10-22 17:31 UTCEchelonGraph re-scored
  9. 2026-10-22 17:31 UTCVendor advisory
  10. 2026-10-22 17:31 UTCGHSA enrichmentGHSA-mxp6-wxxv-r9rj
  11. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  12. 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  13. 2026-10-20 21:26 UTCVendor advisory
  14. 2026-10-20 21:25 UTCNVD update
  15. 2026-10-20 20:27 UTCEchelonGraph re-scored
  16. 2026-10-20 20:27 UTCVendor advisory
  17. 2026-10-20 20:26 UTCMITRE cvelistV5first tracked

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-87864?
CVE-2026-87864 is a high-severity vulnerability; its CVE record was published on October 20, 2026. Enabling CURLOPT_CRLF causes curl to advertise the raw input byte count in the IMAP APPEND {N} literal while transmitting line-ending expanded data. The server reads only $N$ bytes for the payload, causing the remaining overflow bytes to be interpreted and executed as pipelined IMAP commands within…
When was the CVE record for CVE-2026-87864 published?
The CVE record for CVE-2026-87864 was published on October 20, 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 October 30, 2026; the record at its source may have been updated since.
Is CVE-2026-87864 actively exploited?
CVE-2026-87864 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.8% probability of exploitation in the next 30 days (57th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-87864?
CVE-2026-87864 has a CVSS v3.1 base score of 8.1 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-87864?
A fix for CVE-2026-87864 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-87864 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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