CVE-2026-45077

HIGH

8.6

CVSS v3

Description

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.52, 6.4.40, 7.4.12, and 8.0.12, the server:log listener (Symfony\Bridge\Monolog\Command\ServerLogCommand) binds to 0.0.0.0:9911 by default and processes each received frame with unserialize(base64_decode($message)) without authentication, integrity checks, or an allowed_classes allowlist, allowing any reachable host to submit attacker-chosen serialized PHP payloads that can crash the listener and may trigger object-injection gadget effects. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.

CWE-502Deserialization of Untrusted Data CWE-668

How to fix

Remediation Available

symfonyDebian

Fixed in:5.4.53+dfsg-0+deb12u1CVE-2026-45077

Fixed in:6.4.41+dfsg-0+deb13u1CVE-2026-45077

Fixed in:7.4.12+dfsg-1CVE-2026-45077

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Exploit Intelligence

0.67%probability of exploitation in 30 days

49thpercentile

Moderate risk: more likely to be exploited than 49% of all known CVEs.

References

Patch2

Release Notes4

Related Vulnerabilities

Other CWE-502 (Deserialization of Untrusted Data) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-0669	High	7.2	100%	KEV + Ransom	Fix
CVE-2021-44228	Critical	10.0	100%	KEV + Ransom	Fix
CVE-2021-35464	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2025-53770	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2023-29300	Critical	9.8	100%	KEV + Ransom	-
CVE-2025-59287	Critical	9.8	100%	KEV	Fix

Common questions

How do I fix CVE-2026-45077?

Upgrade symfony on debian 12 to 5.4.53+dfsg-0+deb12u1 or later.

Is CVE-2026-45077 being actively exploited?

Not that we know of. CVE-2026-45077 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.67% is the estimated probability that it will be exploited in the next 30 days. That is higher than 49% of all scored CVEs.

How severe is CVE-2026-45077?

CVE-2026-45077 has a CVSS v3 base score of 8.6, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-45077 affect?

Published advisories record a fix for symfony (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-15.