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: 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...

curl: rustls backend silently ignores CURLOPT_CRLFILE when native CA store is active

Hi all, When the rustls backend is configured to use the OS native CA store --ca-native / CURLSSLOPTNATIVECA, any CRL file supplied via --crlfile / CURLOPTCRLFILE is silently ignored. The option is accepted — CURLEOK from curleasysetopt, exit 0 from the command line — and revoked certificates pas...

curl: Trailing-dot IPv4 URL bypasses IP-address guard, allows wildcard DNS SAN match

Hi all, Sorry to ruin anybody's day, but we've discovered another issue when it comes to dots. We've found a TLS certificate verification bypass that lets a trailing-dot IPv4 URL -- https://127.0.0.1./ -- pass peer authentication against a wildcard DNS SAN certificate such as DNS:.0.0.1. The IP...

Rocket.Chat: Autotranslate DDP Method Exposes Private Messages Without Authentication or Room Access Check

Vulnerability description not provided...

curl: TLS verifyhost bypass in rustls, mbedTLS, and wolfSSL when verifypeer=0

The now-well-known CURLOPTSSLVERIFYHOST-bypass-when-CURLOPTSSLVERIFYPEER=0 defect exists in three of curl's TLS backends: rustls EXPERIMENTAL, mbedTLS, and wolfSSL DNS hostnames only. The documented contract at docs/libcurl/opts/CURLOPTSSLVERIFYPEER.md:57-59: The check that the host name in the...

curl: HTTP/2 proxy CONNECT tunnel unbounded 1xx chain (missing Curl_bump_headersize cap in cf-h2-proxy.c)

A malicious HTTPS-on-HTTP/2 proxy can grow a libcurl client's resident set without bound during the CONNECT phase by streaming 1xx informational responses. The CVE-2023-38039 cap MAXHTTPRESPHEADERSIZE, 300 KiB, enforced through Curlbumpheadersize is not applied on the HTTP/2 proxy path. The HTTP/...

curl: HSTS multi-trailing-dot bypass-ish: possible incomplete fix for CVE-2022-30115

Hi all, Honestly, I'm not completely certain about this issue, but I think the CVE-2022-30115 fix "HSTS bypass via trailing dot" is incomplete: the same asymmetry exists for hostnames with two or more trailing dots, so http://example.com../ still gets sent in plaintext when there's a valid HSTS...

curl: Credentials forwarded to HTTP after HTTPS→HTTP same-port redirect — url_set_data_creds uses scheme-blind comparator

Hi all, The recent creds: hold credentials refactor — commit 8f71d0fde5 2026-05-11 https://github.com/curl/curl/commit/8f71d0fde5 — introduced a credential-leak regression on HTTPS→HTTP same-port redirects. -u user:pass and --oauth2-bearer both end up in cleartext after a 302 from https://h:N/ to...

curl: CURLOPT_HSTS_CTRL disables shared HSTS without share guard — use-after-free and double-free

Hi all, CURLOPTHSTSCTRL set to a value without CURLHSTSENABLE unconditionally frees the easy's HSTS object — even when that object is shared via a CURLSH. The result is a use-after-free and a double-free on the shared 48-byte struct hsts block when the share or any other linked easy is later torn...

curl: Kerberos/SPNEGO Connection Reuse Vulnerability

Kerberos/SPNEGO Connection Reuse Vulnerability in curl Summary curl reuses HTTP connections across different users without checking Kerberos state. User B's request can inherit User A's GSS security context, allowing authentication bypass. Affected Versions All curl versions with Kerberos support...

Liberapay: another liberapay member team twitter account broken Link Hijacking via Expired Twitter Account Link

Hello again i discovered that there is another Liberapay profile of Liberapay team member at liberapay.com/mdvhimself contains a link to an expired Twitter account, creating a Broken Link Hijacking BLH vulnerability. An attacker could register the expired handle and control what appears to be an...

Liberapay: Liberapay member team twitter account broken Link Hijacking via Expired Twitter Account Link

The profile of a Liberapay team member contained a link to an expired Twitter account, creating a broken link hijacking vulnerability. The expired Twitter account link was displayed on the member's Liberapay profile and donation page, falsely confirming to donors that the account was legitimate a...

curl: Shared HSTS cache accessed without lock

This is finding F5 in Andrew's report https://github.com/curl/curl/blob/455bebc2c7/lib/hsts.cL160-L168 https://github.com/curl/curl/blob/455bebc2c7/lib/http.cL3571 https://github.com/curl/curl/blob/455bebc2c7/lib/url.cL1441 https://github.com/curl/curl/blob/455bebc2c7/lib/url.cL265...

curl: CURLOPT_PROXY_CRLFILE / CURLOPT_PROXY_ISSUERCERT / CURLOPT_PROXY_ISSUERCERT_BLOB silently ignored on backends that don't support them

From the Mythos report 2026-05-06 F1. CURLOPTPROXYCRLFILE / CURLOPTPROXYISSUERCERT / CURLOPTPROXYISSUERCERTBLOB silently ignored on backends that don't support them — severity Low https://github.com/curl/curl/blob/455bebc2c7/lib/setopt.cL1786-L1797...