ThreatsDay: 24-Year-Old Curl Bug and Smart TVs Turning into Proxy Nodes
Just caught the latest ThreatsDay Bulletin, and frankly, it feels like we're fighting the same ghosts from 2002. That 24-year-old curl vulnerability (CVE-2026-3940) is absolutely wild. It’s a buffer overflow in the SOCKS5 handshake that’s been dormant since the early 2000s. If you’re relying on curl for internal fetching on legacy Linux boxes, you need to check versions immediately.
On top of that, the "Smart TV Proxyware" trend is picking up steam. It’s not elite APT stuff; it’s just cheap commodity malware turning IoT devices into residential proxy nodes. The campaign, tracked as "TVProxy," targets specific WebView vulnerabilities.
I've whipped up a quick Bash one-liner to scan for vulnerable curl versions across your fleet if you have a central inventory:
# Check for curl versions prior to 8.8.0 (vulnerable to CVE-2026-3940)
for host in $(cat host_list.txt); do
ssh -o ConnectTimeout=2 $host "curl -V | grep -E 'curl [0-7]\.[0-9]' && echo 'VULNERABLE: '$host"
done
We're currently wrestling with whether to patch the legacy servers or isolate them behind a bastion host with an HTTP proxy. What’s your play here? Are you patching everything, or just air-gapping the crusty old boxes?
We're seeing the TVProxy activity too. It's annoying because the bandwidth isn't high enough to trigger standard DDoS alerts, so it flies under the radar. I added a simple Suricata rule to catch the user-agent string they're using in the POST requests.
alert http $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"TVProxy User Agent Detected"; flow:to_server,established; content:"TVProxy/1.2"; http.user_agent; sid:1000024; rev:1;)
Regarding the curl bug, patching isn't an option for some of our industrial controllers running embedded Linux. We're strictly egress-filtering at the firewall level, blocking SOCKS5 (port 1080) entirely to those subnets. It's a blunt instrument, but we can't risk the availability of the control systems for a patch right now.
That 24-year timeline is terrifying. It really highlights how much 'supply chain' code we take for granted. I ran a sbom scan on our core apps and found 12 instances of libcurl linked statically. We have to rebuild half the stack from source just to mitigate this. Fun week.
For those stuck with statically linked binaries on legacy hardware, verifying the actual binary composition is crucial before panic-patching. You can check if the compiled-in libcurl actually supports SOCKS5 (and is thus vulnerable) using strings.
strings /usr/bin/legacy_app | grep -E 'SOCKS(4|5)' | head -5
If it returns nothing, that specific build might be safe from this particular overflow vector. It’s a quick triage step while you plan your egress controls or hardware replacement.
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