CVE-2013-3587Public exploitNetwork attack vector

Secret recovery via compressed-response length oracle

Published Feb 21, 2020 · Updated Aug 6, 2024

Information disclosure in compressed HTTPS web applications allows man-in-the-middle attackers to recover response secrets via length analysis. HTTP response compression combines reflected attacker-controlled input with a static secret before encryption, making correct character guesses produce measurably shorter ciphertext. Exploitation requires repeated chosen requests through a victim browser, visibility into response sizes, and a sufficiently stable page that reflects both input and a secret.

CVSS severity5.9
Medium
EPSS probability6.05%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in compressed HTTPS web applications allows man-in-the-middle attackers to recover response secrets via length analysis. HTTP response compression combines reflected attacker-controlled input with a static secret before encryption, making correct character guesses produce measurably shorter ciphertext. Exploitation requires repeated chosen requests through a victim browser, visibility into response sizes, and a sufficiently stable page that reflects both input and a secret.

The record

CVE
CVE-2013-3587
Published
Feb 21, 2020
Updated
Aug 6, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-200, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 21, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 6, 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

4.3NIST NVDAV:N/AC:M/Au:N/C:P/I:N/A:N
2.3CERT/CCAV:N/AC:H/Au:N/C:P/I:N/A:N/E:F/RL:W/RC:C
5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
2.6CERT/CCAV:N/AC:H/Au:N/C:P/I:N/A:N

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-200Exposure of Sensitive Information to an Unauthorized Actor
T1557Adversary-in-the-Middle

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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