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VulnerabilityPublished

CVE-2026-32941: BishopFox sliver · Unthrottled Resource Allocation

Affects BishopFox sliverSource CVE Database V5

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Public exploit available · CVSS 5.7 Medium.

Data as of 1 Nov 2026, 11:02 UTC

CVSS 4.0 base score
5.7Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 23% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 20 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 1 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
BishopFoxsliverAffected
  • <=1.7.3
Fixed in–
GitHubbishopfox/sliverpkg:github/bishopfox/sliverOther threatsAffected
  • <=1.7.3
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2026-32941, organizations should immediately restrict access to the Sliver C2 server to trusted personnel and networks, minimizing the risk of credential compromise. Implement strict credential management and rotate credentials frequently to reduce the window of opportunity for attackers. Monitor network traffic for anomalous patterns such as multiple concurrent yamux streams with unusually large or malformed length prefixes, which may indicate exploitation attempts. Deploy resource limits at the operating system or container level (e.g., cgroups on Linux) to cap memory usage of the Sliver server process, preventing system-wide OOM conditions. Consider isolating the Sliver server on dedicated hosts or virtual machines to contain potential crashes and avoid collateral damage to other critical services. On the implant side, enforce strict input validation and implement upper-bound checks on memory allocations to prevent unbounded resource consumption. Until an official patch is released, consider using alternative C2 frameworks or updated Sliver versions if available. Engage with BishopFox or the community for updates and patches addressing this vulnerability. Finally, conduct regular security assessments to detect and remediate any unauthorized access or implant compromise.

Description

Sliver is a command and control framework that uses a custom Wireguard netstack. Versions 1.7.3 and below contain a Remote OOM (Out-of-Memory) vulnerability in the Sliver C2 server's mTLS and WireGuard C2 transport layer. The socketReadEnvelope and socketWGReadEnvelope functions trust an attacker-controlled 4-byte length prefix to allocate memory, with ServerMaxMessageSize allowing single allocations of up to ~2 GiB. A compromised implant or an attacker with valid credentials can exploit this by sending fabricated length prefixes over concurrent yamux streams (up to 128 per connection), forcing the server to attempt allocating ~256 GiB of memory and triggering an OS OOM kill. This crashes the Sliver server, disrupts all active implant sessions, and may degrade or kill other processes sharing the same host. The same pattern also affects all implant-side readers, which have no upper-bound check at all. The issue was not fixed at the the time of publication.

References

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