CVE-2026-114216: medium-severity vulnerability in mtrudel bandit
Chunk extensions accept bare LF and CR, enabling request smuggling in Bandit
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.3epss 0.6%
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in the HTTP/1.1 chunked body reader of mtrudel bandit allows an unauthenticated remote attacker to smuggle a second request past a front-end proxy via a chunk extension that contains a bare LF.
The chunked reader in lib/bandit/http1/socket.ex takes the chunk-size line to be everything up to the first CRLF and discards everything after ; without checking it against the RFC 9112 chunk-ext grammar, so bare LF, bare CR and other control bytes pass. A proxy that ends the size line at a bare LF reads 2;\nxx\r\n40\r\n... as one request whose second chunk holds a GET /admin, while Bandit ends the body early and dispatches GET /admin as a separate pipelined request. Deployments without such a proxy in front of Bandit are not affected.
This issue affects bandit: from 1.12.4 before 1.14.0.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N
Affected products
mtrudel · banditRelated CVEs — mtrudel bandit
In the same product, most dangerous first.
CVE-2026-39804HIGHWebSocket permessage-deflate inflate has no output-size cap in banditEPSS 0.8%CVE-2026-75484MEDIUMHTTP/2 header field values containing CR, LF or NUL are passed to the application unvalidated in BanditEPSS 0.7%CVE-2026-42786HIGHWebSocket fragmented message reassembly unbounded in banditEPSS 0.6%CVE-2026-39803HIGHHTTP/1 chunked body reader ignores length cap in banditEPSS 0.6%CVE-2026-74836HIGHHTTP/2 connection-window starvation pins Plug processes indefinitely in BanditEPSS 0.6%CVE-2026-39806HIGHHTTP/1 chunked decoder infinite loop on requests with trailer fields in banditEPSS 0.6%
References
https://cna.erlef.org/cves/CVE-2026-114216.htmlhttps://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7ahttps://github.com/mtrudel/bandit/commit/c31e9e3c76dcbfc239a96eabed5341ced7885ae5https://github.com/mtrudel/bandit/security/advisories/GHSA-w5wc-g2hc-g7m2https://osv.dev/vulnerability/EEF-CVE-2026-114216