CVE-2026-6253Public exploitNetwork attack vector

Proxy credential disclosure via stale redirect state

Published May 13, 2026 · Updated May 13, 2026

Credential disclosure in curl 7.14.1 through 8.19.0 allows remote attackers to obtain proxy credentials through a cross-scheme redirect. Curl_http_follow resets origin credentials when a redirect changes the scheme or port but leaves proxy credentials in state, so the second proxy receives the first proxy's Basic authorization value. Exploitation requires separate per-scheme proxies, credentials on the first proxy, no credentials on the second, and redirect following; disclosure is limited to the base64-encoded proxy credential pair.

CVSS severity5.9
Medium
EPSS probability0.72%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Credential disclosure in curl 7.14.1 through 8.19.0 allows remote attackers to obtain proxy credentials through a cross-scheme redirect. Curl_http_follow resets origin credentials when a redirect changes the scheme or port but leaves proxy credentials in state, so the second proxy receives the first proxy's Basic authorization value. Exploitation requires separate per-scheme proxies, credentials on the first proxy, no credentials on the second, and redirect following; disclosure is limited to the base64-encoded proxy credential pair.

The record

CVE
CVE-2026-6253
Published
May 13, 2026
Updated
May 13, 2026
Vendor
curl
Product
curl
Classifications
CWE-522, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 13, 2026CVE publishedPublication date reported by the CVE source.
  2. May 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=7.14.1 <=7.14.1
  2. Affected versionversion=7.15.0 <=7.15.0
  3. Affected versionversion=7.15.1 <=7.15.1
  4. Affected versionversion=7.15.2 <=7.15.2
  5. Affected versionversion=7.15.3 <=7.15.3
  6. Affected versionversion=7.15.4 <=7.15.4
  7. Affected versionversion=7.15.5 <=7.15.5
  8. Affected versionversion=7.16.0 <=7.16.0
  9. Affected versionversion=7.16.1 <=7.16.1
  10. Affected versionversion=7.16.2 <=7.16.2
  11. Affected versionversion=7.16.3 <=7.16.3
  12. Affected versionversion=7.16.4 <=7.16.4
  13. Affected versionversion=7.17.0 <=7.17.0
  14. Affected versionversion=7.17.1 <=7.17.1
  15. Affected versionversion=7.18.0 <=7.18.0
  16. Affected versionversion=7.18.1 <=7.18.1
  17. Affected versionversion=7.18.2 <=7.18.2
  18. Affected versionversion=7.19.0 <=7.19.0
  19. Affected versionversion=7.19.1 <=7.19.1
  20. Affected versionversion=7.19.2 <=7.19.2
  21. Affected versionversion=7.19.3 <=7.19.3
  22. Affected versionversion=7.19.4 <=7.19.4
  23. Affected versionversion=7.19.5 <=7.19.5
  24. Affected versionversion=7.19.6 <=7.19.6
  25. Affected versionversion=7.19.7 <=7.19.7
  26. Affected versionversion=7.20.0 <=7.20.0
  27. Affected versionversion=7.20.1 <=7.20.1
  28. Affected versionversion=7.21.0 <=7.21.0
  29. Affected versionversion=7.21.1 <=7.21.1
  30. Affected versionversion=7.21.2 <=7.21.2
  31. Affected versionversion=7.21.3 <=7.21.3
  32. Affected versionversion=7.21.4 <=7.21.4
  33. Affected versionversion=7.21.5 <=7.21.5
  34. Affected versionversion=7.21.6 <=7.21.6
  35. Affected versionversion=7.21.7 <=7.21.7
  36. Affected versionversion=7.22.0 <=7.22.0
  37. Affected versionversion=7.23.0 <=7.23.0
  38. Affected versionversion=7.23.1 <=7.23.1
  39. Affected versionversion=7.24.0 <=7.24.0
  40. Affected versionversion=7.25.0 <=7.25.0
  41. Affected versionversion=7.26.0 <=7.26.0
  42. Affected versionversion=7.27.0 <=7.27.0
  43. Affected versionversion=7.28.0 <=7.28.0
  44. Affected versionversion=7.28.1 <=7.28.1
  45. Affected versionversion=7.29.0 <=7.29.0
  46. Affected versionversion=7.30.0 <=7.30.0
  47. Affected versionversion=7.31.0 <=7.31.0
  48. Affected versionversion=7.32.0 <=7.32.0
  49. Affected versionversion=7.33.0 <=7.33.0
  50. Affected versionversion=7.34.0 <=7.34.0
  51. Affected versionversion=7.35.0 <=7.35.0
  52. Affected versionversion=7.36.0 <=7.36.0
  53. Affected versionversion=7.37.0 <=7.37.0
  54. Affected versionversion=7.37.1 <=7.37.1
  55. Affected versionversion=7.38.0 <=7.38.0
  56. Affected versionversion=7.39.0 <=7.39.0
  57. Affected versionversion=7.40.0 <=7.40.0
  58. Affected versionversion=7.41.0 <=7.41.0
  59. Affected versionversion=7.42.0 <=7.42.0
  60. Affected versionversion=7.42.1 <=7.42.1
  61. Affected versionversion=7.43.0 <=7.43.0
  62. Affected versionversion=7.44.0 <=7.44.0
  63. Affected versionversion=7.45.0 <=7.45.0
  64. Affected versionversion=7.46.0 <=7.46.0
  65. Affected versionversion=7.47.0 <=7.47.0
  66. Affected versionversion=7.47.1 <=7.47.1
  67. Affected versionversion=7.48.0 <=7.48.0
  68. Affected versionversion=7.49.0 <=7.49.0
  69. Affected versionversion=7.49.1 <=7.49.1
  70. Affected versionversion=7.50.0 <=7.50.0
  71. Affected versionversion=7.50.1 <=7.50.1
  72. Affected versionversion=7.50.2 <=7.50.2
  73. Affected versionversion=7.50.3 <=7.50.3
  74. Affected versionversion=7.51.0 <=7.51.0
  75. Affected versionversion=7.52.0 <=7.52.0
  76. Affected versionversion=7.52.1 <=7.52.1
  77. Affected versionversion=7.53.0 <=7.53.0
  78. Affected versionversion=7.53.1 <=7.53.1
  79. Affected versionversion=7.54.0 <=7.54.0
  80. Affected versionversion=7.54.1 <=7.54.1
  81. Affected versionversion=7.55.0 <=7.55.0
  82. Affected versionversion=7.55.1 <=7.55.1
  83. Affected versionversion=7.56.0 <=7.56.0
  84. Affected versionversion=7.56.1 <=7.56.1
  85. Affected versionversion=7.57.0 <=7.57.0
  86. Affected versionversion=7.58.0 <=7.58.0
  87. Affected versionversion=7.59.0 <=7.59.0
  88. Affected versionversion=7.60.0 <=7.60.0
  89. Affected versionversion=7.61.0 <=7.61.0
  90. Affected versionversion=7.61.1 <=7.61.1
  91. Affected versionversion=7.62.0 <=7.62.0
  92. Affected versionversion=7.63.0 <=7.63.0
  93. Affected versionversion=7.64.0 <=7.64.0
  94. Affected versionversion=7.64.1 <=7.64.1
  95. Affected versionversion=7.65.0 <=7.65.0
  96. Affected versionversion=7.65.1 <=7.65.1
  97. Affected versionversion=7.65.2 <=7.65.2
  98. Affected versionversion=7.65.3 <=7.65.3
  99. Affected versionversion=7.66.0 <=7.66.0
  100. Affected versionversion=7.67.0 <=7.67.0
  101. Affected versionversion=7.68.0 <=7.68.0
  102. Affected versionversion=7.69.0 <=7.69.0
  103. Affected versionversion=7.69.1 <=7.69.1
  104. Affected versionversion=7.70.0 <=7.70.0
  105. Affected versionversion=7.71.0 <=7.71.0
  106. Affected versionversion=7.71.1 <=7.71.1
  107. Affected versionversion=7.72.0 <=7.72.0
  108. Affected versionversion=7.73.0 <=7.73.0
  109. Affected versionversion=7.74.0 <=7.74.0
  110. Affected versionversion=7.75.0 <=7.75.0
  111. Affected versionversion=7.76.0 <=7.76.0
  112. Affected versionversion=7.76.1 <=7.76.1
  113. Affected versionversion=7.77.0 <=7.77.0
  114. Affected versionversion=7.78.0 <=7.78.0
  115. Affected versionversion=7.79.0 <=7.79.0
  116. Affected versionversion=7.79.1 <=7.79.1
  117. Affected versionversion=7.80.0 <=7.80.0
  118. Affected versionversion=7.81.0 <=7.81.0
  119. Affected versionversion=7.82.0 <=7.82.0
  120. Affected versionversion=7.83.0 <=7.83.0
  121. Affected versionversion=7.83.1 <=7.83.1
  122. Affected versionversion=7.84.0 <=7.84.0
  123. Affected versionversion=7.85.0 <=7.85.0
  124. Affected versionversion=7.86.0 <=7.86.0
  125. Affected versionversion=7.87.0 <=7.87.0
  126. Affected versionversion=7.88.0 <=7.88.0
  127. Affected versionversion=7.88.1 <=7.88.1
  128. Affected versionversion=8.0.0 <=8.0.0
  129. Affected versionversion=8.0.1 <=8.0.1
  130. Affected versionversion=8.10.0 <=8.10.0
  131. Affected versionversion=8.10.1 <=8.10.1
  132. Affected versionversion=8.1.0 <=8.1.0
  133. Affected versionversion=8.11.0 <=8.11.0
  134. Affected versionversion=8.11.1 <=8.11.1
  135. Affected versionversion=8.1.1 <=8.1.1
  136. Affected versionversion=8.12.0 <=8.12.0
  137. Affected versionversion=8.12.1 <=8.12.1
  138. Affected versionversion=8.1.2 <=8.1.2
  139. Affected versionversion=8.13.0 <=8.13.0
  140. Affected versionversion=8.14.0 <=8.14.0
  141. Affected versionversion=8.14.1 <=8.14.1
  142. Affected versionversion=8.15.0 <=8.15.0
  143. Affected versionversion=8.16.0 <=8.16.0
  144. Affected versionversion=8.17.0 <=8.17.0
  145. Affected versionversion=8.18.0 <=8.18.0
  146. Affected versionversion=8.19.0 <=8.19.0
  147. Affected versionversion=8.2.0 <=8.2.0
  148. Affected versionversion=8.2.1 <=8.2.1
  149. Affected versionversion=8.3.0 <=8.3.0
  150. Affected versionversion=8.4.0 <=8.4.0
  151. Affected versionversion=8.5.0 <=8.5.0
  152. Affected versionversion=8.6.0 <=8.6.0
  153. Affected versionversion=8.7.0 <=8.7.0
  154. Affected versionversion=8.7.1 <=8.7.1
  155. Affected versionversion=8.8.0 <=8.8.0
  156. Affected versionversion=8.9.0 <=8.9.0
  157. Affected versionversion=8.9.1 <=8.9.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

curl · curlversion=7.14.1 <=7.14.1; version=7.15.0 <=7.15.0; version=7.15.1 <=7.15.1; version=7.15.2 <=7.15.2; version=7.15.3 <=7.15.3; version=7.15.4 <=7.15.4; version=7.15.5 <=7.15.5; version=7.16.0 <=7.16.0; version=7.16.1 <=7.16.1; version=7.16.2 <=7.16.2; version=7.16.3 <=7.16.3; version=7.16.4 <=7.16.4; version=7.17.0 <=7.17.0; version=7.17.1 <=7.17.1; version=7.18.0 <=7.18.0; version=7.18.1 <=7.18.1; version=7.18.2 <=7.18.2; version=7.19.0 <=7.19.0; version=7.19.1 <=7.19.1; version=7.19.2 <=7.19.2; version=7.19.3 <=7.19.3; version=7.19.4 <=7.19.4; version=7.19.5 <=7.19.5; version=7.19.6 <=7.19.6; version=7.19.7 <=7.19.7; version=7.20.0 <=7.20.0; version=7.20.1 <=7.20.1; version=7.21.0 <=7.21.0; version=7.21.1 <=7.21.1; version=7.21.2 <=7.21.2; version=7.21.3 <=7.21.3; version=7.21.4 <=7.21.4; version=7.21.5 <=7.21.5; version=7.21.6 <=7.21.6; version=7.21.7 <=7.21.7; version=7.22.0 <=7.22.0; version=7.23.0 <=7.23.0; version=7.23.1 <=7.23.1; version=7.24.0 <=7.24.0; version=7.25.0 <=7.25.0; version=7.26.0 <=7.26.0; version=7.27.0 <=7.27.0; version=7.28.0 <=7.28.0; version=7.28.1 <=7.28.1; version=7.29.0 <=7.29.0; version=7.30.0 <=7.30.0; version=7.31.0 <=7.31.0; version=7.32.0 <=7.32.0; version=7.33.0 <=7.33.0; version=7.34.0 <=7.34.0; version=7.35.0 <=7.35.0; version=7.36.0 <=7.36.0; version=7.37.0 <=7.37.0; version=7.37.1 <=7.37.1; version=7.38.0 <=7.38.0; version=7.39.0 <=7.39.0; version=7.40.0 <=7.40.0; version=7.41.0 <=7.41.0; version=7.42.0 <=7.42.0; version=7.42.1 <=7.42.1; version=7.43.0 <=7.43.0; version=7.44.0 <=7.44.0; version=7.45.0 <=7.45.0; version=7.46.0 <=7.46.0; version=7.47.0 <=7.47.0; version=7.47.1 <=7.47.1; version=7.48.0 <=7.48.0; version=7.49.0 <=7.49.0; version=7.49.1 <=7.49.1; version=7.50.0 <=7.50.0; version=7.50.1 <=7.50.1; version=7.50.2 <=7.50.2; version=7.50.3 <=7.50.3; version=7.51.0 <=7.51.0; version=7.52.0 <=7.52.0; version=7.52.1 <=7.52.1; version=7.53.0 <=7.53.0; version=7.53.1 <=7.53.1; version=7.54.0 <=7.54.0; version=7.54.1 <=7.54.1; version=7.55.0 <=7.55.0; version=7.55.1 <=7.55.1; version=7.56.0 <=7.56.0; version=7.56.1 <=7.56.1; version=7.57.0 <=7.57.0; version=7.58.0 <=7.58.0; version=7.59.0 <=7.59.0; version=7.60.0 <=7.60.0; version=7.61.0 <=7.61.0; version=7.61.1 <=7.61.1; version=7.62.0 <=7.62.0; version=7.63.0 <=7.63.0; version=7.64.0 <=7.64.0; version=7.64.1 <=7.64.1; version=7.65.0 <=7.65.0; version=7.65.1 <=7.65.1; version=7.65.2 <=7.65.2; version=7.65.3 <=7.65.3; version=7.66.0 <=7.66.0; version=7.67.0 <=7.67.0; version=7.68.0 <=7.68.0; version=7.69.0 <=7.69.0; version=7.69.1 <=7.69.1; version=7.70.0 <=7.70.0; version=7.71.0 <=7.71.0; version=7.71.1 <=7.71.1; version=7.72.0 <=7.72.0; version=7.73.0 <=7.73.0; version=7.74.0 <=7.74.0; version=7.75.0 <=7.75.0; version=7.76.0 <=7.76.0; version=7.76.1 <=7.76.1; version=7.77.0 <=7.77.0; version=7.78.0 <=7.78.0; version=7.79.0 <=7.79.0; version=7.79.1 <=7.79.1; version=7.80.0 <=7.80.0; version=7.81.0 <=7.81.0; version=7.82.0 <=7.82.0; version=7.83.0 <=7.83.0; version=7.83.1 <=7.83.1; version=7.84.0 <=7.84.0; version=7.85.0 <=7.85.0; version=7.86.0 <=7.86.0; version=7.87.0 <=7.87.0; version=7.88.0 <=7.88.0; version=7.88.1 <=7.88.1; version=8.0.0 <=8.0.0; version=8.0.1 <=8.0.1; version=8.10.0 <=8.10.0; version=8.10.1 <=8.10.1; version=8.1.0 <=8.1.0; version=8.11.0 <=8.11.0; version=8.11.1 <=8.11.1; version=8.1.1 <=8.1.1; version=8.12.0 <=8.12.0; version=8.12.1 <=8.12.1; version=8.1.2 <=8.1.2; version=8.13.0 <=8.13.0; version=8.14.0 <=8.14.0; version=8.14.1 <=8.14.1; version=8.15.0 <=8.15.0; version=8.16.0 <=8.16.0; version=8.17.0 <=8.17.0; version=8.18.0 <=8.18.0; version=8.19.0 <=8.19.0; version=8.2.0 <=8.2.0; version=8.2.1 <=8.2.1; version=8.3.0 <=8.3.0; version=8.4.0 <=8.4.0; version=8.5.0 <=8.5.0; version=8.6.0 <=8.6.0; version=8.7.0 <=8.7.0; version=8.7.1 <=8.7.1; version=8.8.0 <=8.8.0; version=8.9.0 <=8.9.0; version=8.9.1 <=8.9.1

Published CVSS scores

5.3Amazon LinuxCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
5.9CISA-ADPCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-522Insufficiently Protected Credentials
T1557Adversary-in-the-Middle

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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