CVE-2021-35940 | Regression of CVE-2017-12613

An out-of-bounds array read in the apr_time_exp*() functions was fixed in the Apache Portable Runtime 1.6.3 release (CVE-2017-12613). The fix for this issue was not carried forward to the APR 1.7.x branch, and hence version 1.7.0 regressed compared to 1.6.3 and is vulnerable to the same issue.

Published: 2021-08-23 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-35940 is rated Low Risk (34.3/100): CVSS High severity, with low exploitation likelihood (EPSS 0.06%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

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-2021-35940

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 2025-11-21 0.31% 0.06% -0.25%
2 2025-11-18 0.05% 0.31% +0.26%
3 2025-03-17 — 0.05% —

Full EPSS history (16 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-35940

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.1 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
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:L)
A normal user session is enough; they don’t have to be admin.
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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.2 [email protected]
3.6 2.0 LOW
AV:L/AC:L/Au:N/C:P/I:N/A:P Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 3.9 4.9 [email protected]

Weakness enumeration for CVE-2021-35940

OS Trackers for CVE-2021-35940

vendor priority summary link
alpine high CVE-2021-35940: 1 source package rows (apr); 7 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 7, open 0. https://security.alpinelinux.org/vuln/CVE-2021-35940
debian not yet assigned CVE-2021-35940 not yet assigned priority: Debian including 1 source packages (apr), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-35940
redhat medium — https://access.redhat.com/security/cve/CVE-2021-35940
suse high CVE-2021-35940 severity important: SUSE including 7 source package names (apr, apr-devel, …), 55 product×package rows across 37 product lines (HPE Helion OpenStack 8, SUSE CaaS Platform 4.0, … (37 product lines)): Known Not Affected 51, Fixed 4. https://www.suse.com/security/cve/CVE-2021-35940/
ubuntu medium CVE-2021-35940 medium priority: Ubuntu including 1 source packages (apr), 8 status rows across 8 suites (bionic, focal, hirsute, impish, jammy, trusty, upstream, xenial): released 6, not-affected 2. https://ubuntu.com/security/CVE-2021-35940

Affected software / configurations for CVE-2021-35940

Vendor Product Version Raw CPE
apache portable_runtime 1.7.0 cpe:2.3:a:apache:portable_runtime:1.7.0:*:*:*:*:*:*:*
oracle http_server 12.2.1.3.0 cpe:2.3:a:oracle:http_server:12.2.1.3.0:*:*:*:*:*:*:*
oracle http_server 12.2.1.4.0 cpe:2.3:a:oracle:http_server:12.2.1.4.0:*:*:*:*:*:*:*

References for CVE-2021-35940

URL Tags
http://mail-archives.apache.org/mod_mbox/www-announce/201710.mbox/%3CCACsi251B8UaLvM-rrH9fv57-zWi0zhyF3275_jPg1a9VEVVoxw%40mail.gmail.com%3E
http://svn.apache.org/viewvc?view=revision&revision=1891198 Vendor Advisory
http://www.openwall.com/lists/oss-security/2021/08/23/1 Mailing List Third Party Advisory
https://dist.apache.org/repos/dist/release/apr/patches/apr-1.7.0-CVE-2021-35940.patch Patch Vendor Advisory
https://lists.apache.org/thread.html/r1c788464a25fbc046a72aff451bc8186386315d92a2dd0349903fa4f%40%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/r317c398ee5736e627f7887b06607e5c58b45a696d352ba8c14615f55%40%3Cdev.apr.apache.org%3E
https://lists.apache.org/thread.html/r54c755c74b9e3846cfd84039b1967d37d2870750a02d7c603983f6ed%40%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/r72479f4dcffaa8a4732d5a0e87fecc4bace4932e28fc26f7d400e2b3%40%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/r72a069753b9363c29732e59ad8f0d22a633fb6a699980407511ac961%40%3Cdev.apr.apache.org%3E
https://lists.apache.org/thread.html/r7bb4a6ed88fc48152174e664aae30ea9a8b058eb5b44cf08cb9beb4b%40%3Cdev.apr.apache.org%3E
https://lists.apache.org/thread.html/r7bb4a6ed88fc48152174e664aae30ea9a8b058eb5b44cf08cb9beb4b%40%3Cdev.httpd.apache.org%3E
https://lists.apache.org/thread.html/ra2868b53339a6af65577146ad87016368c138388b09bff9d2860f50e%40%3Cdev.apr.apache.org%3E Mailing List Vendor Advisory
https://lists.apache.org/thread.html/ra38094406cc38a05218ebd1158187feda021b0c3a1df400bbf296af8%40%3Cdev.apr.apache.org%3E
https://lists.apache.org/thread.html/rafe54755850e93de287c36540972457b2dd86332106aa7817c7c27fb%40%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/rb1f3c85f50fbd924a0051675118d1609e57957a02ece7facb723155b%40%3Cannounce.apache.org%3E
https://www.oracle.com/security-alerts/cpujul2022.html Patch Third Party Advisory
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