CyberSecBulletin
CVE-2023-45853NVD status: Modified

zlib: Integer Overflow or Wraparound

Published Updated By the CyberSecBulletin desk

CVE-2023-45853 is a critical-severity integer overflow or wraparound vulnerability in zlib, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 1.3 as the first without the flaw, so updating zlib to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 3.45% chance of exploitation within 30 days, higher than 89% of scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update zlib to 1.3 or a later version.
  2. Update SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to V3.1.5 or a later version.
  3. Update SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to V3.1.5 or a later version.
  4. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Zlibzlibbefore 1.31.3
SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFPV3.1.0 up to, but not including, V3.1.5V3.1.5
SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFPV3.1.0 up to, but not including, V3.1.5V3.1.5
SiemensSIPLUS S7-1500 CPU 1518-4 PN/DP MFPV3.1.0 up to, but not including, V3.1.5V3.1.5
SmihicaPyminizip0.2.6 and earlierNot stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.19.8CriticalNVD
CVSS 3.18.8HighCISA (ADP)

Official description

MiniZip in zlib through 1.3 has an integer overflow and resultant heap-based buffer overflow in zipOpenNewFileInZip4_64 via a long filename, comment, or extra field. NOTE: MiniZip is not a supported part of the zlib product. NOTE: pyminizip through 0.2.6 is also vulnerable because it bundles an affected zlib version, and exposes the applicable MiniZip code through its compress API.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Integer Overflow or Wraparound

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

How developers prevent this class of flaw

  • Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. If possible, choose a language or compiler that performs automatic bounds checking.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Use libraries or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).

More Integer Overflow or Wraparound vulnerabilities (CWE-190)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in zlib

All zlib vulnerabilities

Recent Integer Overflow or Wraparound vulnerabilities

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