curl: curl --skip-existing has a TOCTOU race that lets a post-check symlink redirect the later download write

Summary: The curl CLI's --skip-existing option performs a separate existence check before the download body is written. In the verified path, curl first calls stat on the target pathname and decides "the file does not exist, so continue", but it does not keep an fd bound to that decision. The...

curl: CVE-2026-8927: env-set cross-proxy Digest auth state leak

AI-assisted preparation note I used AI assistance to help structure and format this report, but the technical findings, PoC, and verification results are based on local testing against curl/libcurl 8.20.0. Summary I found a possible incomplete-fix variant of CVE-2026-7168 in libcurl 8.20.0. The...

Revive Adserver: PHP code injection via unexpected delivery limitation parameter

A vulnerability was reported in Revive Adserver 6.0.6 and earlier versions where user input was not properly validated when saving delivery limitations. This allowed a low-privileged user to inject malicious PHP code into the compiledlimitations field, which could then be executed during banner...

curl: CRLF Injection via Custom HTTP Headers

Summary: libcurl writes user-supplied custom headers directly into the HTTP request buffer without stripping \r\n characters. The raw input pointer origp in Curladdcustomheaders lib/http.c is serialized verbatim into the outgoing request using curlxdynaddfreq, "%s\r\n", origp instead of using the...

curl: Connection reuse ignores haproxyprotocol and HAPROXY_CLIENT_IP settings, allowing PROXY context to persist across transfers

Summary: libcurl's connection pool match logic does not include the CURLOPTHAPROXYPROTOCOL setting or the CURLOPTHAPROXYCLIENTIP value in its connection match key. Two transfers issued through the same Curleasy or via a shared connection cache CURLLOCKDATACONNECT therefore share one TCP connectio...

curl: SSL session-cache peer key omits signature_algorithms: strict-sigalg handle silently resumes a permissive sibling's session

CURLOPTSSLSIGNATUREALGORITHMS policy bypass: SSL session cache key omits sigalgs, allowing a strict-sigalg handle to resume a session negotiated under a permissive policy AI disclosure This report was prepared with the assistance of an AI coding assistant Claude. The behavioral diff pre/post patc...

Monero: Restricted RPC leaks alternative block hashes via /get_alt_blocks_hashes

The /getaltblockshashes RPC endpoint was restricted to prevent unintended access to alternative block hashes. The endpoint had previously been unrestricted...

AWS VDP: Firecracker Out-of-bounds Read/Write Local Privilege Escalation Vulnerability

A vulnerability was discovered in Firecracker versions up to 1.15.1 that could allow a malicious guest to bypass protection mechanisms and perform out-of-bounds read and write operations on the virtio PCI queue. The vulnerability was caused by inconsistencies in the handling of queue activation...

Essity: Unauthenticated Account Registration + Email Verification Bypass + PII Data Leak (2,480 Records) on ████████

A vulnerability was discovered in the portal of the organization. The vulnerability allowed any unauthenticated attacker to register an account, bypass email verification, and access protected API endpoints that leaked 2,480 employee records containing names, emails, and profile URLs. The...

Node.js: NULL pointer dereference in node:sqlite DatabaseSync#applyChangeset() via malformed SQLite changeset

Summary: A 19-byte malformed SQLite changeset passed to Node.js node:sqlite DatabaseSyncapplyChangeset causes a native NULL pointer dereference and terminates the Node.js process. Description: The built-in Node.js node:sqlite API exposes DatabaseSyncapplyChangesetchangeset, options, which accepts...

curl: NULL pointer dereference in libcurl URL API redirect_url() with CURLU_DEFAULT_SCHEME

Summary A NULL pointer dereference appears to exist in libcurl's URL API path when curlurlset handles a relative URL together with CURLUDEFAULTSCHEME on a CURLU handle that has host/path information but no stored u-scheme. The issue is in lib/urlapi.c inside redirecturl, where u-scheme is used in...

curl: TLS peer-verification bypass via mid-transfer ssl_config mutation

Hi all, We want to report a TLS peer-verification issue on current master. The trigger is narrow and requires a specific application usage pattern, but when it fires, a transfer that requests CURLOPTSSLVERIFYPEER=1 can reuse a TLS connection that was established with peer verification disabled...

curl: cookie: case-insensitive path comparison in replace_existing() allows cookie eviction across distinct paths

Hi all, replaceexisting in lib/cookie.c compares cookie paths case-insensitively at two sites. On case-sensitive servers, /Admin and /admin are distinct resources and are supposed to produce distinct jar entries. Because libcurl conflates them, a Set-Cookie at one path silently evicts the cookie ...

curl: CVE-2026-8925: SASL double-free

Hi all, We found a double-free in the GSASL authentication path — Curlauthgsaslissupported frees gsasl-ctx on a failed gsaslclientstart but never nulls the pointer, and then Curlauthgsaslcleanup frees it again unconditionally at connection teardown. The bug lives in two spots...

curl: CVE-2026-8926: password leak with netrc and user in URL

Hey all, Before the following report, I just want to point to a comment from our scanner, where it seems it was already picked up but it was dismissed and the PR was closed later by another commit - https://github.com/curl/curl/pull/20932issuecomment-4072903895 Nonetheless, it appears this issue...

curl: HTTPS proxy connection reuse lets one easy handle inherit another handle's mTLS-authenticated proxy session

Summary: libcurl can reuse an already mTLS-authenticated HTTPS proxy TLS connection for a different easy handle even when that second handle does not have the proxy private key required to establish the session itself. The issue happens because the HTTPS proxy connection reuse identity does not...

curl: CURLOPT_PROXY_CAINFO_BLOB silently activates native CA store on Apple builds

Hi all, CURLOPTPROXYCAINFOBLOB introduced 7.77.0 never sets proxyssl.customcablob. On USEAPPLESECTRUST / CURLCANATIVE builds this causes curl to silently fall back to the system keychain for proxy TLS verification, nullifying the caller's blob-only trust policy. --- Root cause lib/setopt.c handle...

curl: libssh SFTP initialization ignores CURLOPT_TIMEOUT, hangs indefinitely

Hi all, The libssh backend in lib/vssh/libssh.c ignores CURLOPTTIMEOUT / --max-time during SFTP subsystem negotiation. A server that completes SSH authentication and then stalls before answering the SSHFXPINIT packet will pin the curl process indefinitely — no timeout fires, no error is returned,...

curl: Schannel custom-CA path skips Extended Key Usage enforcement

Hi all, We believe the Schannel custom-CA verification path in lib/vtls/schannelverify.c may skip Extended Key Usage enforcement. In particular, a certificate that chains to the trusted custom CA but contains only id-kp-clientAuth, rather than id-kp-serverAuth, may pass peer verification on Windo...

curl: HTTP/3 paused transfer buffers incoming data without bound up to ~1 GiB

Hi all, When a libcurl application's CURLOPTWRITEFUNCTION returns CURLWRITEFUNCPAUSE, libcurl routes subsequent incoming body data through cw-pause lib/cw-pause.c. The bufq inside cw-pause is initialised with BUFQOPTSOFTLIMIT and a chunk size of 16 KiB lib/cw-pause.c:51-52, which causes bufq to...