CVE-2016-9964

redirect() in bottle.py in bottle 0.12.10 doesn't filter a "\r\n" sequence, which leads to a CRLF attack, as demonstrated by a redirect("233\r\nSet-Cookie: name=salt") call.

Published: 2016-12-16 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2016-9964 is rated Moderate Risk (52.8/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.76%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2016-9964

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 1.21% 1.76% +0.55%
2 2026-02-18 1.09% 1.21% +0.12%
3 2025-03-30 — 1.09% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-9964

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.0 MEDIUM
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2016-9964

GitHub Security Advisory for CVE-2016-9964

GHSA-j6f7-hghw-g437 · Severity: high · Ecosystem: pip — bottle.py vulnerable to CRLF Injection

OS Trackers for CVE-2016-9964

vendor priority summary link
debian not yet assigned CVE-2016-9964 not yet assigned priority: Debian including 1 source packages (python-bottle), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2016-9964
suse medium CVE-2016-9964 severity moderate: SUSE including 10 source package names (python-bottle-doc-0.12.19-1.8, python-bottle-doc-0.13.3-160000.2.2, …), 15 product×package rows across 11 product lines (SUSE Linux Enterprise Module for Basesystem 15, SUSE Linux Enterprise Module for Desktop Applications 15, … (11 product lines)): Fixed 15. https://www.suse.com/security/cve/CVE-2016-9964/
ubuntu medium CVE-2016-9964 medium priority: Ubuntu including 1 source packages (python-bottle), 16 status rows across 16 suites (artful, bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, precise, trusty, upstream, xenial, yakkety, zesty): not-affected 11, released 4, ignored 1. https://ubuntu.com/security/CVE-2016-9964

Affected software / configurations for CVE-2016-9964

Vendor Product Version Raw CPE
bottlepy bottle 0.12.10 cpe:2.3:a:bottlepy:bottle:0.12.10:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*

References for CVE-2016-9964

URL Tags
http://www.debian.org/security/2016/dsa-3743 Third Party Advisory
http://www.securityfocus.com/bid/94961 Third Party Advisory VDB Entry
https://github.com/bottlepy/bottle/commit/6d7e13da0f998820800ecb3fe9ccee4189aefb54 Issue Tracking Patch Third Party Advisory
https://github.com/bottlepy/bottle/issues/913 Issue Tracking Patch Third Party Advisory
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