diff --git a/meta/recipes-support/curl/curl/CVE-2026-87864.patch b/meta/recipes-support/curl/curl/CVE-2026-87864.patch
new file mode 100644
index 00000000000..0effc5ac8ac
--- /dev/null
+++ b/meta/recipes-support/curl/curl/CVE-2026-87864.patch
@@ -0,0 +1,55 @@
+From 3b547de301342b347fb3c6ea6ae7979070793a66 Mon Sep 17 00:00:00 2001
+From: Stefan Eissing <stefan@eissing.org>
+Date: Thu, 27 Aug 2026 09:47:53 +0200
+Subject: [PATCH] imap: APPEND CRLF fix
+
+Deny an APPEND operation with CRLF conversion requested as we are unable
+to predict the final upload size and APPEND requires us to announce it
+before starting the upload.
+
+The check for unknown sizes had already been there, but the crlf
+conversion that renders a known size unknown was not accounted for.
+
+Closes #22702
+
+CVE: CVE-2026-87864
+Upstream-Status: Backport [https://github.com/curl/curl/commit/3b547de301342b347fb3c6ea6ae7979070793a66]
+
+(cherry picked from commit 3b547de301342b347fb3c6ea6ae7979070793a66)
+Signed-off-by: Darsh Kelaiya <dkelaiya@cisco.com>
+---
+ lib/imap.c | 11 ++++++++---
+ 1 file changed, 8 insertions(+), 3 deletions(-)
+
+diff --git a/lib/imap.c b/lib/imap.c
+index 0546595..f37568f 100644
+--- a/lib/imap.c
++++ b/lib/imap.c
+@@ -884,7 +884,6 @@ static CURLcode imap_perform_append(struct Curl_easy *data,
+       result = Curl_creader_set_mime(data, postp);
+     if(result)
+       return result;
+-    data->state.infilesize = Curl_creader_client_length(data);
+   }
+   else
+ #endif
+@@ -894,9 +893,15 @@ static CURLcode imap_perform_append(struct Curl_easy *data,
+       return result;
+   }
+ 
+-  /* Check we know the size of the upload */
++  /* Check we know the size of the upload. This takes all readers
++   * into account. Especially crlf conversions which make the size
++   * unpredictable, e.g. -1. */
++  data->state.infilesize = Curl_creader_total_length(data);
+   if(data->state.infilesize < 0) {
+-    failf(data, "Cannot APPEND with unknown input file size");
++    if(data->set.crlf)
++      failf(data, "Cannot APPEND with CRLF conversion making size unknown");
++    else
++      failf(data, "Cannot APPEND with unknown input file size");
+     return CURLE_UPLOAD_FAILED;
+   }
+ 
+-- 
+2.35.6
diff --git a/meta/recipes-support/curl/curl_8.19.0.bb b/meta/recipes-support/curl/curl_8.19.0.bb
index 9a85d470dc5..e039207a0e4 100644
--- a/meta/recipes-support/curl/curl_8.19.0.bb
+++ b/meta/recipes-support/curl/curl_8.19.0.bb
@@ -56,6 +56,7 @@ SRC_URI = "https://curl.se/download/${BP}.tar.xz \
            file://CVE-2026-92386_p1.patch \
            file://CVE-2026-92386_p2.patch \
            file://CVE-2026-107928.patch \
+           file://CVE-2026-87864.patch \
            "
 
 SRC_URI:append:class-nativesdk = " \