CVE-2023-27536

CRITICALNVD 5.99.8
EchelonGraph scoreMEDIUM confidence

“▲” beside the score: it is higher than NVD's CVSS score.

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2023-03-30. NVD baseline CVSS 5.9; sources differ by 3.9.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this weekElevated
9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (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: 1.8%CVSS: 5.9Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

An authentication bypass vulnerability exists libcurl <8.0.0 in the connection reuse feature which can reuse previously established connections with incorrect user permissions due to a failure to check for changes in the CURLOPT_GSSAPI_DELEGATION option. This vulnerability affects krb5/kerberos/negotiate/GSSAPI transfers and could potentially result in unauthorized access to sensitive information. The safest option is to not reuse connections if the CURLOPT_GSSAPI_DELEGATION option has been changed.

CVSS v3
5.9
EG Score
9.8CRITICALmedium confidence
EG Risk
60
EG Risk 60/100

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)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 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 or medium mission impact; Track* at high (mission-essential systems).
Exploitation public PoC (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
1.8%
EPSS %ILE
77th
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 (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
1.8% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-23). 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; Track* at high (mission-essential systems).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 low or medium mission impact; Track* at high (mission-essential systems).

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

Exploitation public PoC (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

March 30, 2023

Last Modified

October 23, 2026

Advisory Details (5)

Auto-updated Oct 14, 2026
Patch available.
Web page

curl: Multiple Vulnerabilities (GLSA 202310-12) — Gentoo security

https://security.gentoo.org/glsa/202310-12
Web page

[SECURITY] Fedora 36 Update: curl-7.82.0-14.fc36 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/36NBD5YLJXXEDZLDGNFCERWRYJQ6LAQW/
Web pageMentions a patch (unverified)

[SECURITY] [DLA 3398-1] curl security update

https://lists.debian.org/debian-lts-announce/2023/04/msg00025.html

Patch Availability(6)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntucurl (7.47.0-1ubuntu2.19+esm8) @ xenial2026-10-23ubuntu
ubuntucurl (7.81.0-1ubuntu1.10) @ jammy2026-10-23ubuntu
redhatcurl-0:7.61.1-22.el8_6.122024-01-25redhat
redhatcurl-0:7.76.1-26.el92023-11-07redhat
redhatcurl-0:7.61.1-30.el8_8.32023-08-08redhat
redhatjbcs-httpd24-curl2023-06-05redhat

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

(16 across 16 ecosystems)
Alpine:v3.14(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 8.0.1-r0: fixed in 8.0.1-r0
—
Alpine:v3.15(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 8.0.1-r0: fixed in 8.0.1-r0
—
Alpine:v3.16(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 8.0.1-r0: fixed in 8.0.1-r0
—
Alpine:v3.17(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 7.88.1-r1: fixed in 7.88.1-r1
—
Alpine:v3.18(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 8.0.0-r0: fixed in 8.0.0-r0
—
Alpine:v3.19(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 8.0.0-r0: fixed in 8.0.0-r0
—
Alpine:v3.20(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 8.0.0-r0: fixed in 8.0.0-r0
—
Alpine:v3.21(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 8.0.0-r0: fixed in 8.0.0-r0
—
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 8.0.0-r0: fixed in 8.0.0-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 8.0.0-r0: fixed in 8.0.0-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 8.0.0-r0: fixed in 8.0.0-r0
—
Debian:10(1)
PackageVulnerable rangeFix by version rangeDependents
curl7.64.0-4 ... 7.64.0-4+deb10u5 (6 versions)
  • every version up to 7.64.0-4+deb10u6: fixed in 7.64.0-4+deb10u6
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
curl7.74.0-1.3 ... 7.74.0-1.3+deb11u7~bpo11+1 (9 versions)
  • every version up to 7.74.0-1.3+deb11u8: fixed in 7.74.0-1.3+deb11u8
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 7.88.1-7: fixed in 7.88.1-7
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 7.88.1-7: fixed in 7.88.1-7
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 7.88.1-7: fixed in 7.88.1-7
—

Weakness Classification(2)

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 31× in last 7d / 72× 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 241 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 141 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-23 23:27 UTCVendor advisory
  2. 2026-10-23 23:27 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  3. 2026-10-23 20:26 UTCEG score recompute
  4. 2026-10-23 20:26 UTCVendor advisory
  5. 2026-10-23 20:26 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  6. 2026-10-23 16:29 UTCEPSS rescoreEPSS 1.8% · 77th percentile
  7. 2026-10-22 21:38 UTCEG score recompute
  8. 2026-10-22 21:38 UTCVendor advisory
  9. 2026-10-22 21:38 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  10. 2026-10-22 16:31 UTCEPSS rescoreEPSS 1.8% · 77th percentile
  11. 2026-10-21 22:43 UTCEG score recompute
  12. 2026-10-21 22:43 UTCVendor advisory
  13. 2026-10-21 22:43 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  14. 2026-10-21 16:29 UTCEPSS rescoreEPSS 1.8% · 77th percentile
  15. 2026-10-20 23:57 UTCEG score recompute
  16. 2026-10-20 23:57 UTCVendor advisory
  17. 2026-10-20 23:57 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  18. 2026-10-20 16:29 UTCEPSS rescoreEPSS 1.8% · 77th percentile
  19. 2026-10-20 01:04 UTCEG score recompute
  20. 2026-10-20 01:04 UTCVendor advisory
  21. 2026-10-20 01:04 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  22. 2026-10-19 16:29 UTCEPSS rescoreEPSS 1.8% · 77th percentile
  23. 2026-10-19 00:00 UTCEG score recompute
  24. 2026-10-19 00:00 UTCVendor advisory
  25. 2026-10-19 00:00 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
Show 75 more
  1. 2026-10-18 16:29 UTCEPSS rescoreEPSS 1.8% · 77th percentile
  2. 2026-10-18 08:08 UTCEG score recompute
  3. 2026-10-18 01:13 UTCEG score recompute
  4. 2026-10-18 01:13 UTCVendor advisory
  5. 2026-10-18 01:13 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  6. 2026-10-17 16:29 UTCEPSS rescoreEPSS 1.8% · 77th percentile
  7. 2026-10-17 02:25 UTCEG score recompute
  8. 2026-10-17 02:25 UTCVendor advisory
  9. 2026-10-17 02:25 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  10. 2026-10-16 16:35 UTCEPSS rescoreEPSS 1.8% · 77th percentile
  11. 2026-10-16 03:16 UTCEG score recompute
  12. 2026-10-16 03:16 UTCVendor advisory
  13. 2026-10-16 03:16 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  14. 2026-10-15 16:29 UTCEPSS rescoreEPSS 1.8% · 77th percentile
  15. 2026-10-14 23:27 UTCVendor advisory
  16. 2026-10-14 23:27 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  17. 2026-10-14 22:52 UTCVendor advisory
  18. 2026-10-14 22:52 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  19. 2026-10-14 19:58 UTCEG score recompute
  20. 2026-10-14 19:58 UTCVendor advisory
  21. 2026-10-14 19:57 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  22. 2026-10-14 16:29 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  23. 2026-10-13 16:29 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  24. 2026-10-13 16:09 UTCVendor advisory
  25. 2026-10-13 16:08 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  26. 2026-10-12 17:20 UTCEG score recompute
  27. 2026-10-12 17:20 UTCVendor advisory
  28. 2026-10-12 17:20 UTCGHSA enrichmentGHSA-4f9f-mpmj-4c52 · GitHub severity CRITICAL · GitHub CVSS 9.8
  29. 2026-10-12 16:30 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  30. 2026-10-11 21:56 UTCEG score recompute
  31. 2026-10-11 13:45 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  32. 2026-10-10 19:57 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  33. 2026-10-09 20:05 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  34. 2026-10-08 17:06 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  35. 2026-10-07 23:45 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  36. 2026-10-06 15:15 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  37. 2026-10-05 17:41 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  38. 2026-10-03 14:23 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  39. 2026-10-02 16:23 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  40. 2026-10-01 19:47 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  41. 2026-09-30 16:20 UTCEG score recompute
  42. 2026-09-30 15:01 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  43. 2026-09-29 15:16 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  44. 2026-09-28 13:49 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  45. 2026-09-27 13:42 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  46. 2026-09-26 00:22 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  47. 2026-09-24 14:01 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  48. 2026-09-23 16:17 UTCOSV refresh
  49. 2026-09-23 13:45 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  50. 2026-09-22 14:45 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  51. 2026-09-20 20:14 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  52. 2026-09-16 14:05 UTCEPSS rescoreEPSS 1.6% · 74th percentile
  53. 2026-09-13 16:44 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  54. 2026-09-12 14:58 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  55. 2026-09-11 14:50 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  56. 2026-09-11 09:34 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  57. 2026-09-08 21:57 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  58. 2026-09-07 15:59 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  59. 2026-09-06 13:45 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  60. 2026-09-05 15:25 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  61. 2026-09-04 13:58 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  62. 2026-09-04 10:59 UTCOSV refresh
  63. 2026-09-04 05:04 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  64. 2026-09-02 14:09 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  65. 2026-09-01 13:51 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  66. 2026-08-30 19:15 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  67. 2026-08-30 01:19 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  68. 2026-08-28 21:38 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  69. 2026-08-27 14:23 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  70. 2026-08-26 14:43 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  71. 2026-08-25 13:46 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  72. 2026-08-24 14:14 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  73. 2026-08-23 00:17 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  74. 2026-08-21 23:46 UTCEPSS rescoreEPSS 1.6% · 73rd percentile
  75. 2026-08-20 22:53 UTCEPSS rescoreEPSS 1.6% · 73rd percentile

Frequently asked(5)

What is CVE-2023-27536?
CVE-2023-27536 is a critical-severity vulnerability; its CVE record was published on March 30, 2023. An authentication bypass vulnerability exists libcurl <8.0.0 in the connection reuse feature which can reuse previously established connections with incorrect user permissions due to a failure to check for changes in the CURLOPTGSSAPIDELEGATION option. This vulnerability affects…
When was the CVE record for CVE-2023-27536 published?
The CVE record for CVE-2023-27536 was published on March 30, 2023. 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 23, 2026; the record at its source may have been updated since.
Is CVE-2023-27536 actively exploited?
CVE-2023-27536 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.8% probability of exploitation in the next 30 days (77th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2023-27536?
CVE-2023-27536 has a CVSS v3 base score of 5.9 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.8 (CRITICAL).
How do I remediate CVE-2023-27536?
A fix for CVE-2023-27536 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2023-27536 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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