This Red Hat security advisory addresses four vulnerabilities in curl, including an authentication bypass via incorrect connection reuse with Negotiate (CVE-2026-1965, CVSS 6.5), OAuth2 bearer token leakage during redirects (CVE-2026-3783, CVSS 5.3), and a high-severity SSH host key bypass enabling MITM attacks (CVE-2026-9547, CVSS 7.4). Based on authoritative NVD data, affected versions are haxx curl 7.10.6 to 8.18.0 for CVE-2026-1965, 7.33.0 to 8.18.0 for CVE-2026-3783, and 7.69.0 to 8.20.0 for CVE-2026-9547. The fixed versions are curl 8.19.0 for the first two CVEs and 8.21.0 for CVE-2026-9547.
Red Hat Product Errata RHSA-2026:55439 - Security Advisory Issued: 2026-08-17 Updated: 2026-08-17 RHSA-2026:55439 - Security Advisory Overview Updated Packages Synopsis Important: curl security update Type/Severity Security Advisory: Important Red Hat Lightspeed patch analysis Identify and remediate systems affected by this advisory. View affected systems Topic An update for curl is now available for Red Hat Enterprise Linux 9. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section. Description The curl packages provide the libcurl library and the curl utility for downloading files from servers using various protocols, including HTTP, FTP, and LDAP. Security Fix(es): curl: curl: Authentication bypass due to incorrect connection reuse with Negotiate authentication (CVE-2026-1965) curl: curl: Information disclosure via OAuth2 bearer token leakage during HTTP(S) redirect (CVE-2026-3783) curl: curl: Man-in-the-middle attack via SSH host key bypass (CVE-2026-9547) curl: curl: Insecure connection establishment due to TLS configuration mismatch (CVE-2026-8286) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section. Solution For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Affected Products Red Hat Enterprise Linux for x86_64 9 x86_64 Red Hat Enterprise Linux for x86_64 - Extended Update Support 9.8 x86_64 Red Hat Enterprise Linux for IBM z Systems 9 s390x Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 9.8 s390x Red Hat Enterprise Linux for Power, little endian 9 ppc64le Red Hat Enterprise Linux for Power, little endian - Extended Update Support 9.8 ppc64le Red Hat Enterprise Linux for ARM 64 9 aarch64 Red Hat Enterprise Linux for ARM 64 - Extended Update Support 9.8 aarch64 Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.8 ppc64le Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.8 x86_64 Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.8 aarch64 Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.8 s390x Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 9.8 x86_64 Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 9.8 aarch64 Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 9.8 ppc64le Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 9.8 s390x Fixes BZ - 2446448 - CVE-2026-1965 curl: curl: Authentication bypass due to incorrect connection reuse with Negotiate authentication BZ - 2446450 - CVE-2026-3783 curl: curl: Information disclosure via OAuth2 bearer token leakage during HTTP(S) redirect BZ - 2496758 - CVE-2026-9547 curl: curl: Man-in-the-middle attack via SSH host key bypass BZ - 2496763 - CVE-2026-8286 curl: curl: Insecure connection establishment due to TLS configuration mismatch CVEs CVE-2026-1965 CVE-2026-3783 CVE-2026-8286 CVE-2026-9547 References https://access.redhat.com/security/updates/classification/#important Note: More recent versions of these packages may be available. Click a package name for more details. Red Hat Enterprise Linux for x86_64 9 SRPM curl-7.76.1-40.el9_8.5.src.rpm SHA-256: 5a455f6c35ae1069b8c54ade4c9d0d3d260134f76bee10f22efef9683c31b03f x86_64 curl-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 273736810bf95bd5efd1ee4942d349c51aeba23941dc28026d2cb2cf6719a2e3 curl-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: 44d72618634998542d102daea90709b35731f70d4ad10c881241155df00c1156 curl-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: 44d72618634998542d102daea90709b35731f70d4ad10c881241155df00c1156 curl-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 3aa7bc9c3ecb30f31af27b90ea41859282bc64fbeed03e7aa241c1f3af0c7119 curl-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 3aa7bc9c3ecb30f31af27b90ea41859282bc64fbeed03e7aa241c1f3af0c7119 curl-debugsource-7.76.1-40.el9_8.5.i686.rpm SHA-256: 2e2795af233575a3cf556e3417672a416f3a0388359f81c7a5816bae0c5a1d2b curl-debugsource-7.76.1-40.el9_8.5.i686.rpm SHA-256: 2e2795af233575a3cf556e3417672a416f3a0388359f81c7a5816bae0c5a1d2b curl-debugsource-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 53bc904437456da407da4e5016b03cdebb13a1249eae4ec20d2bb68ac20fd730 curl-debugsource-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 53bc904437456da407da4e5016b03cdebb13a1249eae4ec20d2bb68ac20fd730 curl-minimal-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 2f2a6163de9fcf67d986a6ddefbfe5126f82b94374afd4fb3b5e6f7f3dce6559 curl-minimal-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: e62249c94da1da272a143f5960ec019f52b1b5e271c9ab47c4575647bfadb82a curl-minimal-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: e62249c94da1da272a143f5960ec019f52b1b5e271c9ab47c4575647bfadb82a curl-minimal-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: bdc51c80ea8f2114b539a35537e79082965e5a2a14715d77d4af3cc45dafbf45 curl-minimal-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: bdc51c80ea8f2114b539a35537e79082965e5a2a14715d77d4af3cc45dafbf45 libcurl-7.76.1-40.el9_8.5.i686.rpm SHA-256: a9912d920ec6333edca95d44ff60715668146d93e2a6f161a29cabc7c58b5e11 libcurl-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 428b87ca3eb808d769f6f0f68019a97d3c487c86268ccff2ab7ad7223beab01e libcurl-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: 7c245337e6b03426c1a07c6970577e111c785de57f427803a65c4855febd863c libcurl-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: 7c245337e6b03426c1a07c6970577e111c785de57f427803a65c4855febd863c libcurl-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: e6215094d09605ca225a2d014c54fe2fb0c35acb9004699a74183376d8270f5b libcurl-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: e6215094d09605ca225a2d014c54fe2fb0c35acb9004699a74183376d8270f5b libcurl-devel-7.76.1-40.el9_8.5.i686.rpm SHA-256: ec650e15b5dc1fad6cbd4ea62a0ac21bbc278dd5ba8b7471eabf39610d128e97 libcurl-devel-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 2c606bcd568a0eb3384ac44abf1f451c2ad1c4f5672787a5fce4fe578c29f83a libcurl-minimal-7.76.1-40.el9_8.5.i686.rpm SHA-256: f72c83cd7f0e1828c26022bca2f3c225c3b8fba3f75401da12b358084debd8b8 libcurl-minimal-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: b57b81fd9f950f427cdc2d09e4682e7a5f45fdcce8419a216fa9be9ce28949e0 libcurl-minimal-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: 706473276d97932f938a359b98cac3bf844fabe19bdbbc279311d9cb7653bc72 libcurl-minimal-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: 706473276d97932f938a359b98cac3bf844fabe19bdbbc279311d9cb7653bc72 libcurl-minimal-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 3edd548aad2ae8815c12c78fad97b1d76df0841137e8efb53dd58510376404bb libcurl-minimal-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 3edd548aad2ae8815c12c78fad97b1d76df0841137e8efb53dd58510376404bb Red Hat Enterprise Linux for x86_64 - Extended Update Support 9.8 SRPM curl-7.76.1-40.el9_8.5.src.rpm SHA-256: 5a455f6c35ae1069b8c54ade4c9d0d3d260134f76bee10f22efef9683c31b03f x86_64 curl-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 273736810bf95bd5efd1ee4942d349c51aeba23941dc28026d2cb2cf6719a2e3 curl-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: 44d72618634998542d102daea90709b35731f70d4ad10c881241155df00c1156 curl-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: 44d72618634998542d102daea90709b35731f70d4ad10c881241155df00c1156 curl-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 3aa7bc9c3ecb30f31af27b90ea41859282bc64fbeed03e7aa241c1f3af0c7119 curl-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 3aa7bc9c3ecb30f31af27b90ea41859282bc64fbeed03e7aa241c1f3af0c7119 curl-debugsource-7.76.1-40.el9_8.5.i686.rpm SHA-256: 2e2795af233575a3cf556e3417672a416f3a0388359f81c7a5816bae0c5a1d2b curl-debugsource-7.76.1-40.el9_8.5.i686.rpm SHA-256: 2e2795af233575a3cf556e3417672a416f3a0388359f81c7a5816bae0c5a1d2b curl-debugsource-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 53bc904437456da407da4e5016b03cdebb13a1249eae4ec20d2bb68ac20fd730 curl-debugsource-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 53bc904437456da407da4e5016b03cdebb13a1249eae4ec20d2bb68ac20fd730 curl-minimal-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 2f2a6163de9fcf67d986a6ddefbfe5126f82b94374afd4fb3b5e6f7f3dce6559 curl-minimal-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: e62249c94da1da272a143f5960ec019f52b1b5e271c9ab47c4575647bfadb82a curl-minimal-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: e62249c94da1da272a143f5960ec019f52b1b5e271c9ab47c4575647bfadb82a curl-minimal-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: bdc51c80ea8f2114b539a35537e79082965e5a2a14715d77d4af3cc45dafbf45 curl-minimal-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: bdc51c80ea8f2114b539a35537e79082965e5a2a14715d77d4af3cc45dafbf45 libcurl-7.76.1-40.el9_8.5.i686.rpm SHA-256: a9912d920ec6333edca95d44ff60715668146d93e2a6f161a29cabc7c58b5e11 libcurl-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 428b87ca3eb808d769f6f0f68019a97d3c487c86268ccff2ab7ad7223beab01e libcurl-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: 7c245337e6b03426c1a07c6970577e111c785de57f427803a65c4855febd863c libcurl-debuginfo-7.76.1-40.el9_8.5.i686.rpm SHA-256: 7c245337e6b03426c1a07c6970577e111c785de57f427803a65c4855febd863c libcurl-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: e6215094d09605ca225a2d014c54fe2fb0c35acb9004699a74183376d8270f5b libcurl-debuginfo-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: e6215094d09605ca225a2d014c54fe2fb0c35acb9004699a74183376d8270f5b libcurl-devel-7.76.1-40.el9_8.5.i686.rpm SHA-256: ec650e15b5dc1fad6cbd4ea62a0ac21bbc278dd5ba8b7471eabf39610d128e97 libcurl-devel-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: 2c606bcd568a0eb3384ac44abf1f451c2ad1c4f5672787a5fce4fe578c29f83a libcurl-minimal-7.76.1-40.el9_8.5.i686.rpm SHA-256: f72c83cd7f0e1828c26022bca2f3c225c3b8fba3f75401da12b358084debd8b8 libcurl-minimal-7.76.1-40.el9_8.5.x86_64.rpm SHA-256: b57b81fd9f950f427cdc2d09e4682e7a5f45fdcce8419a216fa9be9ce28949e0 lib