trillium-http and trillium-client vulnerable to HTTP Request/Response Splitting

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Trillium is a composable toolkit for building internet applications with async rust. In `trillium-http` prior to 0.3.12 and `trillium-client` prior to 0.5.4, insufficient validation of outbound header values may lead to request splitting or response splitting attacks in scenarios where attackers have sufficient control over headers. This only affects use cases where attackers have control of request headers, and can insert "\r\n" sequences. Specifically, if untrusted and unvalidated input is inserted into header names or values. Outbound `trillium_http::HeaderValue` and `trillium_http::HeaderName` can be constructed infallibly and were not checked for illegal bytes when sending requests from the client or responses from the server. Thus, if an attacker has sufficient control over header values (or names) in a request or response that they could inject `\r\n` sequences, they could get the client and server out of sync, and then pivot to gain control over other parts of requests or responses. (i.e. exfiltrating data from other requests, SSRF, etc.) In `trillium-http` versions 0.3.12 and later, if a header name is invalid in server response headers, the specific header and any associated values are omitted from network transmission. Additionally, if a header value is invalid in server response headers, the individual header value is omitted from network transmission. Other headers values with the same header name will still be sent. In `trillium-client` versions 0.5.4 and later, if any header name or header value is invalid in the client request headers, awaiting the client Conn returns an `Error::MalformedHeader` prior to any network access. As a workaround, Trillium services and client applications should sanitize or validate untrusted input that is included in header values and header names. Carriage return, newline, and null characters are not allowed.

Source published

24 Jan 2024 19:38:41 UTC

Source modified

30 May 2025 14:16:20 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 6.8 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

Trillium is a composable toolkit for building internet applications with async rust. In `trillium-http` prior to 0.3.12 and `trillium-client` prior to 0.5.4, insufficient validation of outbound header values may lead to request splitting or response splitting attacks in scenarios where attackers have sufficient control over headers. This only affects use cases where attackers have control of request headers, and can insert "\r\n" sequences. Specifically, if untrusted and unvalidated input is inserted into header names or values. Outbound `trillium_http::HeaderValue` and `trillium_http::HeaderName` can be constructed infallibly and were not checked for illegal bytes when sending requests from the client or responses from the server. Thus, if an attacker has sufficient control over header values (or names) in a request or response that they could inject `\r\n` sequences, they could get the client and server out of sync, and then pivot to gain control over other parts of requests or responses. (i.e. exfiltrating data from other requests, SSRF, etc.) In `trillium-http` versions 0.3.12 and later, if a header name is invalid in server response headers, the specific header and any associated values are omitted from network transmission. Additionally, if a header value is invalid in server response headers, the individual header value is omitted from network transmission. Other headers values with the same header name will still be sent. In `trillium-client` versions 0.5.4 and later, if any header name or header value is invalid in the client request headers, awaiting the client Conn returns an `Error::MalformedHeader` prior to any network access. As a workaround, Trillium services and client applications should sanitize or validate untrusted input that is included in header values and header names. Carriage return, newline, and null characters are not allowed.

Source published

Jan 24, 2024, 7:38:41 PM (timezone not stated)

Source modified

May 30, 2025, 2:16:20 PM (timezone not stated)

Observed here

9 Nov 2026 00:04:24 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 6.8 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

Trillium is a composable toolkit for building internet applications with async rust. In `trillium-http` prior to 0.3.12 and `trillium-client` prior to 0.5.4, insufficient validation of outbound header values may lead to request splitting or response splitting attacks in scenarios where attackers have sufficient control over headers. This only affects use cases where attackers have control of request headers, and can insert "\r\n" sequences. Specifically, if untrusted and unvalidated input is inserted into header names or values. Outbound `trillium_http::HeaderValue` and `trillium_http::HeaderName` can be constructed infallibly and were not checked for illegal bytes when sending requests from the client or responses from the server. Thus, if an attacker has sufficient control over header values (or names) in a request or response that they could inject `\r\n` sequences, they could get the client and server out of sync, and then pivot to gain control over other parts of requests or responses. (i.e. exfiltrating data from other requests, SSRF, etc.) In `trillium-http` versions 0.3.12 and later, if a header name is invalid in server response headers, the specific header and any associated values are omitted from network transmission. Additionally, if a header value is invalid in server response headers, the individual header value is omitted from network transmission. Other headers values with the same header name will still be sent. In `trillium-client` versions 0.5.4 and later, if any header name or header value is invalid in the client request headers, awaiting the client Conn returns an `Error::MalformedHeader` prior to any network access. As a workaround, Trillium services and client applications should sanitize or validate untrusted input that is included in header values and header names. Carriage return, newline, and null characters are not allowed.

Source published

24 Jan 2024 20:15:53 UTC

Source modified

17 Jun 2026 07:13:17 UTC

Observed here

24 Oct 2026 23:17:22 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 6.8 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

CVSS 3.1 · [email protected] · Primary · 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

### Summary Insufficient validation of outbound header values may lead to request splitting or response splitting attacks in scenarios where attackers have sufficient control over outbound headers. ### Details Outbound `trillium_http::HeaderValue` and `trillium_http::HeaderName` can be constructed infallibly and were not checked for illegal bytes when sending requests from the client or responses from the server. Thus, if an attacker has sufficient control over header values (or names) in a request or response that they could inject `\r\n` sequences, they could get the client and server out of sync, and then pivot to gain control over other parts of requests or responses. (i.e. exfiltrating data from other requests, SSRF, etc.) ### Patches #### trillium-http >= 0.3.12: * If a header name is invalid in server response headers, the specific header and any associated values are omitted from network transmission. * If a header value is invalid in server response headers, the individual header value is omitted from network transmission. Other headers values with the same header name will still be sent. #### trillium-client >= 0.5.4: * If any header name or header value is invalid in the client request headers, awaiting the client Conn returns an `Error::MalformedHeader` prior to any network access. ### Workarounds trillium services and client applications should sanitize or validate untrusted input that is included in header values and header names. Carriage return, newline, and null characters are not allowed. ### Impact This only affects use cases where attackers have control of outbound headers, and can insert "\r\n" sequences. Specifically, if untrusted and unvalidated input is inserted into header names or values. ### A note on timing from @jbr on behalf of `trillium-rs` @divergentdave filed this vulnerability many months ago but I did not see it until the evening of Jan 23, 2024. Patches were issued less than 24h after reading the vulnerability. The [security policy](https://github.com/trillium-rs/trillium/blob/main/SECURITY.md) has been [updated](https://github.com/trillium-rs/trillium/commit/b27950ceae52aa7a0f482494fe67b6069234d417) to avoid delays like this in the future.

Source published

24 Jan 2024 20:20:38 UTC

Source modified

10 Sep 2026 03:50:09 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

Publisher rating · MODERATE

### Summary Insufficient validation of outbound header values may lead to request splitting or response splitting attacks in scenarios where attackers have sufficient control over outbound headers. ### Details Outbound `trillium_http::HeaderValue` and `trillium_http::HeaderName` can be constructed infallibly and were not checked for illegal bytes when sending requests. Thus, if an attacker has sufficient control over header values (or names) in a request that they could inject `\r\n` sequences, they could get the client and server out of sync, and then pivot to gain control over other parts of requests or responses. (i.e. exfiltrating data from other requests, SSRF, etc.) ### Patches #### trillium-client >= 0.5.4: * If any header name or header value is invalid in the client request headers, awaiting the client Conn returns an `Error::MalformedHeader` prior to any network access. ### Workarounds trillium client applications should sanitize or validate untrusted input that is included in header values and header names. Carriage return, newline, and null characters are not allowed. ### Impact This only affects use cases where attackers have control of outbound headers, and can insert "\r\n" sequences. Specifically, if untrusted and unvalidated input is inserted into header names or values. ### Credit Discovered and reported by [@divergentdave](https://github.com/divergentdave)

Source published

23 Jan 2024 12:00:00 UTC

Source modified

12 Oct 2026 18:00:04 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.

### Summary Insufficient validation of outbound header values may lead to request splitting or response splitting attacks in scenarios where attackers have sufficient control over outbound headers. ### Details Outbound `trillium_http::HeaderValue` and `trillium_http::HeaderName` can be constructed infallibly and were not checked for illegal bytes when sending responses from the server. Thus, if an attacker has sufficient control over header values (or names) in an outbound response that they could inject `\r\n` sequences, they could get the client and server out of sync, and then pivot to gain control over other parts of requests or responses. (i.e. exfiltrating data from other requests, SSRF, etc.) ### Patches #### trillium-http >= 0.3.12: * If a header name is invalid in server response headers, the specific header and any associated values are omitted from network transmission. * If a header value is invalid in server response headers, the individual header value is omitted from network transmission. Other headers values with the same header name will still be sent. ### Workarounds trillium services should sanitize or validate untrusted input that is included in header values and header names. Carriage return, newline, and null characters are not allowed. ### Impact This only affects use cases where attackers have control of outbound headers, and can insert "\r\n" sequences. Specifically, if untrusted and unvalidated input is inserted into header names or values. ### Credit Discovered and reported by [@divergentdave](https://github.com/divergentdave)

Source published

23 Jan 2024 12:00:00 UTC

Source modified

12 Oct 2026 18:00:04 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.