CVE-2021-29935Public exploitNetwork attack vector

Memory corruption via panic-unsafe URI formatting

Published Apr 1, 2021 · Updated Aug 3, 2024

Use-after-free in Rocket before 0.4.7 allows remote attackers to access freed string memory when a URI display callback panics. uri::Formatter transmutes a borrowed string to a static lifetime, stores it in StackVec, and fails to remove it when the invoked formatter panics. Reachability requires an application-supplied formatting implementation that panics during a remotely triggered formatting path; later access can disclose or corrupt process memory.

CVSS severity7.3
High
EPSS probability1.03%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Rocket before 0.4.7 allows remote attackers to access freed string memory when a URI display callback panics. uri::Formatter transmutes a borrowed string to a static lifetime, stores it in StackVec, and fails to remove it when the invoked formatter panics. Reachability requires an application-supplied formatting implementation that panics during a remotely triggered formatting path; later access can disclose or corrupt process memory.

The record

CVE
CVE-2021-29935
Published
Apr 1, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-416, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
7.3GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
7.3RustSecCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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