CVE-2023-49081 | aiohttp's ClientSession is vulnerable to CRLF injection via version

Exp

aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. Improper validation made it possible for an attacker to modify the HTTP request (e.g. to insert a new header) or create a new HTTP request if the attacker controls the HTTP version. The vulnerability only occurs if the attacker can control the HTTP version of the request. This issue has been patched in version 3.9.0.

Published: 2023-11-30 Last update: 2025-11-04 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-49081 is rated High Exploit Risk (63.1/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.87%). 2 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

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

Public exploit references (Exploit-DB) for CVE-2023-49081

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2023-49081

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 0.47% 0.87% +0.40%
2 2026-05-28 0.39% 0.47% +0.08%
3 2026-05-23 — 0.39% —

Full EPSS history (15 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-49081

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.2 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/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:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 2.7 [email protected]
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
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:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 1.4 [email protected]

Weakness enumeration for CVE-2023-49081

GitHub Security Advisory for CVE-2023-49081

GHSA-q3qx-c6g2-7pw2 · Severity: medium · Ecosystem: pip — aiohttp's ClientSession is vulnerable to CRLF injection via version

OS Trackers for CVE-2023-49081

vendor priority summary link
debian not yet assigned CVE-2023-49081 not yet assigned priority: Debian including 1 source packages (python-aiohttp), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-49081
redhat medium — https://access.redhat.com/security/cve/CVE-2023-49081
suse medium CVE-2023-49081 severity moderate: SUSE including 8 source package names (python-aiohttp-doc-3.6.0-150100.3.15.1, python3-aiohttp-3.6.0-150100.3.15.1, …), 74 product×package rows across 67 product lines (Image SLES15-SP3-BYOS-Azure, Image SLES15-SP3-HPC-BYOS-Azure, … (67 product lines)): Fixed 74. https://www.suse.com/security/cve/CVE-2023-49081/
ubuntu medium CVE-2023-49081 medium priority: Ubuntu including 1 source packages (python-aiohttp), 12 status rows across 12 suites (bionic, focal, jammy, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 5, released 4, ignored 3. https://ubuntu.com/security/CVE-2023-49081

Affected software / configurations for CVE-2023-49081

Vendor Product Version Raw CPE
aiohttp aiohttp < 3.9.0 cpe:2.3:a:aiohttp:aiohttp:*:*:*:*:*:*:*:*

References for CVE-2023-49081

cvelogic Threat Intelligence