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🛡️ CVE-2024-49768 — waitress

🔴 CVSS 9.5 — Critical ✅ No Known Exploit CWE-367 OSV
9.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Waitress has request processing race condition in HTTP pipelining with invalid first request

Impact

A remote client may send a request that is exactly recv_bytes (defaults to 8192) long, followed by a secondary request using HTTP pipelining.

When request lookahead is disabled (default) we won't read any more requests, and when the first request fails due to a parsing error, we simply close the connection.

However when request lookahead is enabled, it is possible to process and receive the first request, start sending the error message back to the client while we read the next request and queue it. This will allow the secondary request to be serviced by the worker thread while the connection should be closed.

Patches

Waitress 3.0.1 fixes the race condition.

Workarounds

Disable channel_request_lookahead, this is set to 0 by default disabling this feature. For this vulnerability this value is required to be changed from the default.

For more information

If you have any questions or comments about this advisory:

Thanks

  • m4yfly and urn1ce From TianGong Team of Legendsec at Qi'anxin Group.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity low, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: Low — limited, and the attacker does not choose what is affected.
  • Availability impact: None.

Weakness class

CVE-2024-49768 is classified as CWE-367: Time-of-check Time-of-use Race Condition. The state checked and the state acted upon can differ, because it may change between the two steps.

Affected software

CVE-2024-49768 is recorded against 1 package.

  • waitress (from 2.0.0 up to 3.0.1)

Timeline and source

Published on 29 October 2024 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from OSV.

References

github.com (Advisory)
github.com (Fix)

Other advisories for this package

waitress has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-367: Time-of-check Time-of-use Race Condition) in other software:

CVE-2024-49768 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity CRITICAL
CVSS Score 9.5
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
CWE CWE-367
Public Exploit ✅ No
Source OSV
Published 2024-10-29
Updated 2026-08-20
Modified 2026-06-17

Affected Packages

Software From version Fixed in
waitress 2.0.0 3.0.1

Similar Threats

Exploit Protection

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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